Renal disease in pregnancy

Note

Values considered normal when not pregnant may reflect decreased renal function in pregnancy. Creatinine >75mol/L and urea >4.5mmol/L merit further investigation. See p 15. Glycosuria in pregnancy may reflect altered renal physiology and not necessarily imply hyperglycaemia.

Treat asymptomatic bacteriuria in pregnancy. Check that infection and bacteriuria clear with treatment.

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Abortion (miscarriage)

Abortion is the loss of a pregnancy before 24 weeks' gestation. 20-40% of pregnancies miscarry, mostly in the first trimester. Most present with bleeding PV. Diagnosis may not be straightforward (consider ectopics): have a low threshold for doing an ultrasound scan. Pregnancy tests remain +ve for several days after fetal death.

Management of early pregnancy bleeding

Consider the following:

• Is she shocked? There may be blood loss, or products of conception in the cervical canal (remove them with sponge forceps).
• Has pain and bleeding been worse than a period? Have products of conception been seen? (Clots may be mistaken for products.)
• Is the os open? The external os of a multigravida usually admits a fingertip.
• Is uterine size appropriate for dates?
• Is she bleeding from a cervical lesion and not from the uterus?
• What is her blood group? If RhD-ve does she need anti-D?

If symptoms are mild and the cervical os is closed it is a threatened abortion. Rest is advised but probably does not help. 75% will settle. Threatened abortion (especially second trimester) is associated with risk of subsequent preterm rupture of membranes and preterm delivery so book mother at a hospital with good neonatal facilities.

If symptoms are severe and the os is open it is an inevitable abortion or, if most of the products have already been passed, an incomplete abortion. If bleeding is profuse, consider ergometrine 0.5mg IM. If there is unacceptable pain or bleeding, or much retained tissue on ultrasound, arrange evacuation of retained products of conception (ERPC). Expectant management is used when the volume of retained products is small eg <15mm across on transvaginal scan; when 15-50mm, medical management eg with mifepristone may be offered (benefit may not be conclusive).17

Missed abortion

The fetus dies but is retained. There has usually been bleeding and the uterus is small for dates. Confirm with ultrasound. Mifepristone and misoprostol may be used to induce uterine evacuation if the uterus is small but 50% will require surgical evacuation if uterine products are >5cm2 in the trans- verse plane; >6cm2 in the sagittal plane.1 Surgical evacuation is required for larger uteruses.

Mid-trimester abortion

This is usually due to mechanical causes, eg cervical incompetence (rapid, painless delivery of a live fetus), uterine abnormalities; or chronic maternal disease (eg DM, SLE). An incompetent cervix can be strengthened by a cervical encirclage suture at ~16 weeks of pregnancy. It is removed prior to labour.

After a miscarriage

Miscarriage may be a bereavement. Give the parents space to grieve, and to ask why it happened and if it will happen again. Fetal products should be incinerated but if the mother requests alternative disposal (eg to bury herself) her wishes should be respected.1

Most early pregnancy losses are due to aneuploidy and abnormal fetal development; 10% to maternal illness, eg pyrexia. 2nd trimester loss may be due to infection, eg CMV. Bacterial vaginosis has been implicated. Most subsequent pregnancies are normal although at increased risk.

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Anaemia in pregnancy

Even a small PPH may become life-threatening if the mother is anaemic. Anaemia predisposes to infection, and makes heart failure worse. Worn-out, anaemic mothers may not cope with their offspring. Anaemia is the main cause of perinatal problems associated with malaria; above all, anaemia is a leading mechanism by which poverty exacts its morbid toll in pregnancy.

WHO definition of anaemia of pregnancy

Hb <11g/dL. By this standard 50% of women not on haematinics become anaemic. The fall in Hb is steepest around 20 weeks' gestation, and is physiological (p 6); indeed failure of Hb to fall below 10.5g/dL (but not further than ~9.5g/dL) indicates ↑risk of low birth weight or premature delivery.

Who is prone to anaemia?

Those who start pregnancy anaemic, eg from menorrhagia, hookworm, malaria, with haemoglobinopathies; those with frequent pregnancies, twin pregnancy, or a poor diet.

Antenatal screening

includes Hb estimation at booking, at 28 and 36 weeks. In black patients do sickle-cell tests, in others of foreign descent consider Hb electrophoresis for other haemoglobinopathies. From malarious areas consider malaria, and thick films. See p 27.

Treatment

Pregnancy increases iron needs by 700 1400mg (per pregnancy), provided for by a pregnancy-induced 9-fold increase in iron absorption. Iron and folate supplements (and prevention against hookworm and malaria) are recommended in many developing countries.13

Offer iron to those likely to be iron deficient (see above) or who would refuse transfusion if haemorrhaging (p 85). Parenteral iron may be given (to those with iron deficiency anaemia not tolerating oral iron) as iron dextran or iron sucrose. Beware anaphylaxis. Use only if cardiopulmonary rescuscitation facilities to hand. Hb rises over 6 weeks, so late severe anaemia (Hb <9g/dL) may need blood transfusion. One unit of blood increases the Hb by ~0.7g/dL.

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HIV in pregnancy and labour

Many babies are not infected in utero but become so during parturition. Most mothers at risk of passing on HIV to the next generation (vertical transmission) do not want to know their HIV status, or cannot afford to find out. (If their husband is uninfected, what is the chance of him remaining loyal?) In our section on perinatal HIV (p 34) we comment that anti-retrovirals and caesarean section can prevent vertical transmission but this is not much help if the nearest hospital is 3h away by wheelbarrow, and has only basic drugs. What is needed is much more cost-effective advice.

• Only give blood transfusions if absolutely necessary.
• Avoid any procedure likely to lead to maternal cells contacting fetal blood eg external cephalic version, and amniocentesis.
• In instrumental deliveries, try to avoid abrasions of the fetal skin. Vacuum extractors may be preferable to forceps.
• When you clamp the cord, ensure there is no maternal blood on it.
• Artificial rupture of membranes and episiotomies should be left to the last possible moment, or avoided altogether.
• Avoid fetal scalp electrodes, and doing fetal scalp blood samples.
• If the membranes have ruptured, avoid long labours transmission risk doubles after ruptured for 4h and increases by 2%/h thereafter up to 24h.MET14
• During caesarean sections, open the last layer by blunt dissection, to avoid minor cuts to the baby from the scalpel.
• Rinse the baby after birth; wipe the face away from mouth, eyes, and nostrils.
• Unless there is apnoea, avoid suction catheters to aspirate mucus from the nostrils. The baby's face is likely to be covered with the mother's blood at this stage, and you do not want to force HIV into nostrils.
• Health programmes are likely to end up encouraging breast feeding if there is no satisfactory alternative. Humanized milk is expensive, and may indicate to the mother's neighbours that she is HIV+ve. Using humanized milk might also compound problems by removing the one free method of contraception: lactational amenorrhoea. But studies from Nairobi showed 70% formula fed babies alive and disease-free at 2yrs vs 58% if breast fed. Most transmission occurred in the first 6 months. These babies had access to the city water supply.RCT15 Breast milk transmission was 16%. Also HIV+ve mothers in developing countries who breast feed may die sooner.
• Offer advice on avoiding future pregnancies. This is not an easy area. Encouraging the use of condoms is fine, but many will want the added protection of the Pill. IUCDs promote bleeding, and may increase spread to men. This may also be a problem with the progestogen-only Pill, but note that the latter may cause less ectropion than the combined Pill, and this might be advantageous. Sterilization is the hardest choice, especially when the mother now has no living children because of HIV.

Traditionally, drug therapy for HIV in pregnant patients consisted of mono-therapy with zidovudine in contrast to non-pregnant women treated with combination therapy. Combination therapies are recommended in pregnancy.1 Antiretrovirals are becoming more available in many developing countries but there is a long way to go before all infected mothers will have access to them. Get expert advice.

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Normal labour

is that occurring after 37 weeks' gestation. It should result in the spontaneous vaginal delivery of the baby within 24h of the onset of regular spontaneous contractions. It is often heralded by ashow, ie a plug of cervical mucus and a little blood as the membranes strip from the os. The membranes may then rupture.

The first stage of labour

is the time from the onset of regular contractions until the cervix is fully dilated (no cervix felt around the head). The cervix initially effaces (becomes shorter and softer) before it dilates. A satisfactory rate of dilatation from 3cm dilated is 1cm/h. The first stage generally takes up to 12h in a primip, and 7.5h in a multip. During the first stage check maternal pulse, BP, and T° half-hourly; assess the contractions every 15min, their strength (you should not be able to indent the uterus with the fingers during a contraction) and their frequency (ideally 3-4 per 10min, lasting up to 1min). Carry out vaginal examination eg every 4h to assess the degree of cervical dilatation, the position and the station of the head (measured in cm above the ischial spines) and note the degree of moulding (p 42). Note the state of the liquor (see p 72). Test maternal urine 4-hourly for ketones and protein. If the mother becomes ketotic set up an IVI and give her 10% dextrose.1 Measure the fetal heart rate (if not being continuously monitored) every 15min. Note the rate before, during, and immediately after a contraction.

The second stage

is the time from complete cervical dilatation until the baby is born.

The mother has an urge to push and uses abdominal muscles and the Valsalva manoeuvre to help move the baby. As the head descends, the perineum stretches and the anus gapes. Normal time for second stage is 45-120min in a primip, and 15-45min in a multip. Prevent a precipitate delivery (and so intracranial bleeding) by pressure over the perineum.

Delay in clamping the cord for 30sec and holding the baby 20cm below the introitus results in higher haematocrit levels, so reducing transfusion and oxygen supplement requirements in premature babies.

The third stage

is delivery of the placenta. As the uterus contracts to a <24-week size after the baby is born, the placenta separates from the uterus through the spongy layer of the decidua basalis. It then buckles and a small amount of retroplacental haemorrhage aids its removal.

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Multiple pregnancy

Features

Early pregnancy: uterus too large for dates; hyperemesis. Later there may be polyhydramnios. The signs are that >2 poles may be felt; there is a multiplicity of fetal parts; 2 fetal heart rates may be heard (reliable if heart rates differ by >10 beats/min). Ultrasound confirms diagnosis (and at 10-14 weeks, can distinguish monochorionic from dichorionic twins).1

Complications during pregnancy

Polyhydramnios; pre-eclampsia is more common (10% in singleton pregnancies; 30% in twins); anaemia is more common (iron and folate requirements are increased). There is an increased incidence of APH (6% for twins, vs 4.7% for singletons) due to both abruption and placenta praevia (large placenta).

Fetal complications

Perinatal mortality for twins is 36.7/1000 (8/1000 if single; 73/1000 for triplets; and 204 for higher multiples). The main problem is prematurity. Mean gestation for twins is 37 weeks, for triplets 33 weeks. Growth restricted babies (p 52) are more common (growth the same as singletons up to 24 weeks but may be slower thereafter). Malformation rates are increased 2-4 times, especially in monozygotic twins. Severe disability rate 1.5% for singletons, 3.4% for twins. Ultrasound is the main diagnostic test. Selective fetocide (eg with intracardiac potassium chloride) is best used before 20 weeks if indicated. With monozygotic twins, intermingling blood supply may result in disparate twin size and one being born plethoric (hence jaundiced later), the other anaemic. If one fetus dies in utero it may become a fetus papyraceous which may be aborted later or delivered prematurely.

Complications of labour

PPH is more common (4-6% in singletons, 10% in twins). Malpresentation is common (cephalic/cephalic 40%, cephalic/breech 40%, breech/breech 10%, cephalic/transverse (Tv) 5%, breech/Tv 4%, Tv/Tv 1%). Rupturing of vasa praevia, increased rates of cord prolapse (0.6% singleton, 2.3% twins), premature separation of the placenta and cord entanglement (especially monozygous) may all present difficulties at labour. Despite modern technology some twins remain undiagnosed, staff are unprepared, and syntometrine may be used inappropriately, so delaying delivery of the second twin. Epidural anaesthesia is helpful for versions.

Management

• Ensure adequate rest (need not entail admission).
• Use ultrasound for diagnosis and monthly checks on fetal growth.
• Give additional iron and folate to the mother during pregnancy.
• More antenatal visits, eg weekly from 30 weeks (risk of eclampsia↑).
• Tell the mother how to identify preterm labour, and what to do.
• Consider induction at 40 weeks. Have an IVI running in labour and an anaesthetist available at delivery. Paediatricians (preferably one for each baby) should be present at delivery for resuscitation should this be necessary (second twins have a higher risk of asphyxia).

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Minor symptoms of pregnancy

Symptoms and signs in the first 10 weeks

Early symptoms are amenorrhoea, nausea, vomiting, and bladder irritability. Breasts engorge, nipples enlarge (darken at 12 weeks), Montgomery's tubercles (sebaceous glands on nipples) become prominent. Vulval vascularity increases and the cervix softens and looks bluish (4 weeks). At 6 10 weeks the uterine body is more globular. Temperature rises (<37.8 °C).

Headaches, palpitations, and fainting are all commoner in pregnancy. Sweating and feeling hot are also common, due to a dilated peripheral circulation. Management: Increase fluid intake and take showers.

Urinary frequency is due to pressure of the fetal head on the bladder in later pregnancy. Exclude UTI.

Abdominal pain

Breathlessness is common.

Constipation tends to occur as gut motility decreases. Adequate oral fluids and a high fibre diet help combat it. Avoid stimulant laxatives they increase uterine activity in some women. Increased venous distensibility and pelvic congestion predispose to haemorrhoids (if they prolapse, rest the mother head down, apply ice packs and replace them), and varicose veins. Resting with feet up, and properly worn elastic stockings help.

Reflux oesophagitis and heartburn occur as pyloric sphincter relaxation allows irritant bile to reflux into the stomach. Cigarettes and spices should be avoided, small meals taken, and antacids may be used. Use more pillows, and a semi-recumbent position.

Third trimester backache

Due to pelvic ligament and muscle relaxation, pain tends to be worse at night. A firm mattress, flat shoes, standing with back straight, and pelvic support from physiotherapy all help.

Carpal tunnel syndrome (p 714) in pregnancy is due to fluid retention. Advise wrist splints until delivery cures the problem.

Itch/itchy rashes are common (up to 25%) and may be due to the usual causes (OHCM p 76, check LFT see p 26) or to pruritic eruption of pregnancy (PEP = prurigo of pregnancy) an intensely itchy papular/plaque rash on the abdomen and limbs. PEP is most common in first pregnancies beyond 35 weeks' gestation. Emollients and weak topical steroids ease it. Delivery cures it. If vesicles are present, think of pemphigoid gestationis (PG): a rare (1:50,000) condition which may cause fatal heat loss and cardiac failure; the baby may be briefly affected; refer early (prednisolone may be needed). PG may recur in later pregnancies.

Ankle oedema

This is very common, almost normal manifestation of pregnancy. Measure BP and check urine for protein (pre-eclampsia, p 48). Check legs for DVT. It often responds to rest and leg elevation. Reassure that it is harmless (unless pre-eclampsia).

Leg cramps 33% get cramp, the latter half of pregnancy, severe in 5%, often worse at night. Raising the foot of the bed by 20cm will help.

Chloasma

This is a patch of darker pigmentation.
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Epilepsy in pregnancy

Epilepsy de novo is rare in pregnancy. Epilepsy affects ~0.5% of women of child-bearing age so a unit with 3000 deliveries per year has ~15 pregnant epileptic women at any one time. Seizure rates worsen in most women having >1 seizure/month. Sleep deprivation in the last month of pregnancy may contribute to seizures. It is unusual for seizures to recur in pregnancy when preceded by a long seizure-free period.

Complications

Maternal

Risk of 3rd trimester vaginal bleeding. 1% convulse in labour.

Fetal:

• Haemorrhagic disease of newborn can occur with enzyme inducers (below).
• Congenital malformation (UK register suggests 5.9% affected with sodium valproate, 2.3% with carbamazepine, 2.1% with lamotrigine). Malformation is commoner if 2 anticonvulsants are used and with higher doses.

Fetal valproate syndrome

Signs: major organ system anomalies ± autism ± small ears, small broad nose, a long upper lip, shallow philtrum & micro/retrognathia.1

Cleft lip

Associated with maternal epilepsy only, the relative risk for a fetus having clefts compared to the non-epileptic population is 1.0 if the mother develops epilepsy after the pregnancy; 2.4 if she develops it after conception (but has no drugs); 4.7 if fetus is exposed to anticonvulsants. Phenytoin and phenobarbital cause clefts and congenital heart disease. Neural tube defects are commoner with valproate (& carbamazepine) so screen for these (p 10). Neurodevelopmental delay is seen with valproate, seen as lower verbal intelligence quotient (also seen in the offspring of those having frequent tonic clonic seizures in pregnancy.2

Management

Get expert help (refer to epilepsy specialist to optimize and monitor medication: only make antiepileptic changes on expert advice). Avoid trimethadione and paramethadione (both very teratogenic). Where anticonvulsants are needed keep the dose of the chosen drug as low as possible. Aim for 1 drug only. Give folic acid supplements, eg 5mg/24h PO from prior to conception. Give vitamin K1 20mg/24h PO to the mother from 36 weeks if she is taking enzyme inducers ie carbamazepine, ethosuximide, phenytoin, primidone, phenobarbitone (oxcarbazine and topiramate are subjects of debate).3 Screen for neural tube defects and heart disease if relevant (above). Treat status epilepticus as in the non-pregnant but monitor the fetus. It is associated with significant fetal and maternal mortality. Deliver in hospital with resuscitation facilities (1-2% epileptic women convulse in labour and the subsequent 48 hours)-and avoid early discharge. Give baby vitamin K 1mg IM at birth. If seizures are likely, to avoid dropping the baby during a seizure, advise changing the baby on mat on floor, and feeding sitting on floor supported by cushions, and only bath the baby with supervision. Mothers may breast feed (phenobarbital can cause drowsiness in the baby). Ask for review of epilepsy drugs postnatally eg at 12 weeks.

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Forceps

Forceps are designed with a cephalic curve, which fits around the fetal head, and a pelvic curve which fits the pelvis. Short-shanked (eg Wrigley's) forceps are used for lift out deliveries, when the head is on the perineum; long-shanked (eg Neville Barnes) for higher deliveries, when the sagittal suture lies in the AP diameter. Kielland's forceps have a reduced pelvic curve, making them suitable for rotation (only in experienced hands).

Conditions of use

The head must be engaged; the membranes ruptured; the position of the head known and the presentation suitable, ie vertex or face (mentoanterior); there must not be cephalo pelvic disproportion (moulding not excessive); the cervix must be fully dilated and the uterus contracting, and analgesia adequate (perineal infiltration for the episiotomy; pudendal blocks may be sufficient for mid-cavity forceps and ventouse deliveries but not for Kielland's). The bladder must be empty.

Indications for use

Forceps may be used when there is delay in the second stage: this is frequently due to failure of maternal effort (uterine inertia or just tiredness), epidural analgesia, or malpositions of the fetal head. They may be used when there is fetal distress or a prolapsed cord, or eclampsia— all occurring only in the second stage. They are also used to prevent undue maternal effort, eg in cardiac disease, respiratory disease, pre-eclampsia. They are used for the after-coming head in breech deliveries.

Technique

Learn from demonstration. The following is an aide-m moire for non-rotational forceps. Place the mother in lithotomy position with her bottom just over the edge of the delivery bed. Use sterilizing fluid to clean the vulva and perineum; catheterize; check the position of the head. Insert pudendal block and infiltrate the site of the episiotomy (not necessary if she has an epidural). Assemble the blades to check they fit, with the pelvic curve pointing upwards. The handle which lies in the left hand is the left blade and is inserted first (to the mother's left side) and then the right: the handles should lock easily. Traction must not be excessive (the end of bed is not for extra leverage!). Synchronize traction with contractions, guiding the head downwards initially. Do a large episiotomy when the head is at the vulva. Change the direction of traction to up and out as the head passes out of the vulva. If baby needs resuscitation, give to paediatrician. Give vitamin K (p 120). Is thromboprophylaxis needed? See p 16.

Forceps complications

Maternal: Trauma (commoner than with ventouse). Fetal: facial bruising, VII paralysis (usually resolves); brachial plexus injury.

Ventouse

The ventouse, or vacuum extractor, associated with less maternal trauma than forceps is preferred worldwide, but not in the UK. It may be used in preference to rotational forceps because, as traction is applied, with the cup over the posterior fontanelle, rotation during delivery will occur. It can be used through a partially dilated cervix (primips should be almost fully dilated, multips >6cm), but should not be used if the head is above the ischial spines. It is contraindicated for face presentations and for premature babies. A cup is applied with a suction force of 0.8kg/cm2. The baby's scalp is sucked up to form a chignon, which resolves in 2 days. There is increased rate of fetal cephalhaematoma (p 90) and neonatal jaundice so give vitamin K (p 120). Maternal trauma still occurs in ~11%.

If ventouse, low forceps, or mid forceps are needed for 1st delivery, spontaneous rates for 2nd delivery are 91%, 88%, 82% respectively in the absence of induction or augmentation.60 Women having vaginal delivery are more satisfied with the birth, less anxious about the baby, and more likely to breast feed. Only about a third will have vaginal delivery after previous Caesarean Section.

Indications for forceps delivery1

Relative indications (ventouse or Caesarean an alternative)

• Delay or maternal exhaustion in second stage.
• Dense epidural block with diminished urge to push.
• Rotational instrumental delivery for malposition of head.
• Suspected fetal distress.

Specific indications for forceps (forceps delivery is usually superior to ventouse or Caesarean in these circumstances)

• Assisted breech delivery, forceps to deliver head.
• Assisted delivery of preterm infant <34 weeks gestation.
• Controlled delivery of head at Caesarean section.
• Assisted delivery with face presentation.
• Assisted delivery with suspected coagulopathy or thrombocytopenia in fetus.
• Instrumental delivery where maternal condition precludes pushing (eg cardiac disease, respiratory disease).
• Cord prolapse in second stage of labour.
• Instrumental delivery under GA.

1 R Patel 2004 BMJ 328 1303

Obstetric brachial plexus palsy (OBPI)

OBPI complicates <0.5% of live births.

Risk factors

Large birth weight; shoulder dystocia with prolonged 2nd stage of labour; forceps delivery; vacuum extraction; diabetes mellitus; breech presentation. Formerly, the cause of OBPI was excessive lateral traction applied to the fetal head at delivery, in association with anterior shoulder dystocia.

Instrumental-associated OBPI may arise because of nerve stretch injuries after rotations of >90° or from direct compression of the forceps blade in the fetal neck.61 Not all cases of brachial plexus palsy are attributable to traction. Intrauterine factors may play some role.62

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Dystocia

Dystocia is difficulty in labour. There may be problems with the passenger (large baby, see impacted shoulders = shoulder dystocia p 72, or an abnormal presentation), the passages (for ideal pelvis, see p 42 note that cervical dystocia may be a problem after biopsy of the cervix, or a consequence of female genital mutilation p 246) or of propulsion (the uterine powers). Cephalopelvic disproportion results if diameters are unfavourable (p 42).

The pelvis

The ideal pelvis has a round brim (ie gynaecoid), but 15% of women have a long oval brim (anthropoid). A very flat brim is less favourable (platypoid); occurring in 5% of women over 152cm (5ft), it occurs in 30% of women <152cm. Spinal scoliosis, kyphosis, sacralization of the L5 vertebra, spondylolisthesis and pelvic fractures may all affect pelvic anatomy. Rickets and polio were formerly important causes of pelvic problems. Suspect pelvic contraction if the head is not engaged by 37 weeks in a Caucasian primip (after excluding placenta praevia).

The presentation

Cephalic presentations are less favourable, the less flexed the head. Transverse lie and brow presentations will always need caesarean section: face and OP (p 71) presentations may deliver vaginally but are more likely to fail to progress. Breech presentation is particularly unfavourable if the fetus >3.5kg.

The uterine powers

Contractions start in the fundus and propagate downwards. The intensity and duration of contractions are greatest at the fundus, but the contraction reaches its peak in all parts of the uterus simultaneously. Normal contractions occur at a rate of 3 per 10min, they should last up to 75sec, the contraction peak usually measures 30“60mmHg, and the resting uterine tone between them should be 10“15mmHg. Uterine muscle has the property of retraction. The shortening of the muscle fibres encourages cervical dilatation.

Uterine dysfunction

Contractions may be hypotonic (low resting tone, low contraction peaks) or they may be normotonic but occur too infrequently. These dysfunctions can be corrected by augmentation with oxytocin (p 64). Whenever oxytocin is used discuss with a senior obstetrician. Pain and fear cause release of catecholamines which can inhibit uterine activity. Thus adequate analgesia is needed (p 66) and may speed the progress of labour.

Cervical dystocia

Failure of cervical dilatation may be due to previous trauma, repair, cone biopsy, and cauterization. It is difficult to distinguish from failure to dilate due to uterine dysfunction though the latter should respond to oxytocin (note the important difference between primips and multips, p 64). The treatment for cervical dystocia is delivery by caesarean section.

Consequences of prolonged labour

Neonatal mortality rises with prolonged labour as does maternal morbidity (especially infection). With modern management of labour, careful monitoring of progress in labour (p 64) takes place to diagnose delay early, and treat it as necessary, to prevent prolonged labour occurring.

When there is dystocia, ask ˜is safe vaginal delivery possible?

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Prematurity

Premature infants are those born before 37 weeks' gestation. Prevalence: ~6% singletons, 46% of twin, 79% of triplet or higher order deliveries. About 2% are before 32 weeks when neonatal problems are greatest. In 25%, delivery is elective (p 62). 10% are due to multiple pregnancy; 25% are due to APH, cervical incompetence, amnionitis, uterine abnormalities, diabetes, polyhydramnios, pyelonephritis, or other infections. In 40% the cause is unknown, but abnormal genital tract colonization (bacterial vaginosis) with ureaplasma and Mycoplasma hominis is implicated, either as a risk factor or risk marker. We also know that consumption of fish oil in pregnancy can ‘birth weight by “risk of recurrence of preterm delivery.1

Managing preterm rupture of membranes (PROM)

Admit; do T° MSU, and HVS using a sterile bivalve speculum. Assess for causes/associations: eg abruption, twins, and polyhydramnios. If liquor is not obvious its presence is suggested if nitrazine sticks (pH-sensitive) turn black (false +ve with infected vaginal discharge, semen, blood, and urine). In 80%, membrane rupture initiates labour. The problem with the 20% who do not go into labour is balancing advantages of remaining in utero (maturity and surfactant‘) against the threat of infection (causes 20% of neonatal deaths after PROM). Intrauterine infection supervenes after membranes have ruptured in 10% by 48h, 26% by 72h, 40% by >72h. Prophylactic antibiotics may allow labour to be delayed. If infection develops, do blood culture and give IV antibiotics (eg ampicillin 500mg/6h IV + netilmicin 150mg/12h IV) and expedite labour (p 62). Antibiotics for ~24h pre-labour, “rates of intraventricular haemorrhage and periventricular malacia (below) in the baby. If labour supervenes, allow it to progress. If liquor stops draining for >48h (rare) slowly mobilize the mother.42

Management of preterm labour

In 50% contractions cease spontaneously. Treating the cause (eg pyelonephritis) may make it cease. Attempts to suppress contractions (tocolysis) are unlikely to succeed if membranes are ruptured or the cervix >4cm dilated. The rationale for tocolytic use was that delay of preterm labour would improve fetal outcome without causing harm to mother or fetus. Trials have shown them to be of almost no clinical benefit, and only nifedipine is associated with improvement of fetal outcome. It is quite reasonable not to use tocolytic drugs; though they may be considered desirable in certain circumstances eg to give time for corticosteroids to work; or for in utero transfer.2 Use only between 24"33 weeks. Consider transfer to hospital with SCBU facilities. Call paediatrician to attend to the baby at birth. See cord-cutting recommendations p 58.

Tocolytic drugs

Absolute CI: chorioamnionitis, fetal death or lethal abnormality, condition (fetal or maternal) needing immediate delivery. Relative CI: fetal growth restriction or distress, pre-eclampsia, placenta praevia, abruption, cervix >4cm. β-sympathomimetics, associated with maternal fluid overload and pulmonary oedema are not recommended. Atosiban (licensed in Europe) has less maternal effects, has not been shown to benefit the fetus, and is expensive. Nifedipine is as effective, and associated with less newborn respiratory distress and admission to intensive care. Regimen: nifedipine 20mg PO then 10"20mg/6"8h PO according to uterine activity (unlicensed indication). SE: “BP; headache; flushing; pulse‘ (transient); myocardial infarction (very rare).43

1

S Olsen 2002 BMJ i447 If fish oil intake is low, small amounts of n-3 fatty acids provided as fish or fish oil may protect against prematurity & low birth weight.

2

K Groom 2004 The Obstetrician and Gynaecologist 6 41

Glucocorticoids

Betametasone 12mg IM followed by a second dose 12 hours later, (or, less favoured dexamethasone 6mg/12h × 4 doses) promote fetal surfactant production, lowering mortality and complications of RDS (p 118) by 40"50%. They also help close patent ductuses and protect against periventricular malacia, a cause of cerebral palsy. Use between 24 and 34 weeks. Avoid if maternal systemic infection eg TB.

If diabetic, monitor glucose. Benefit is maximal after 24h; effects last a week.

Prematurity, survival, and disability the figures

ne major, landmark question is: Is the baby over 28 weeks' gestation?

• The disability rate is 25% if gestation is <28 weeks but half this if gestation is 28"29 weeks.
• 10% of those who survive at gestations <28 weeks will never be independently mobile, or communicate intelligibly with others.
• Only 4% of babies born before 24 weeks will survive, and of survivors, >50% will be severely disabled.
• Use of surfactant (p 118) has not reduced the viability threshold, or rates of severe disability in babies born at <28 weeks' gestation.
• Of babies born >30 weeks' gestation, in the absence of deformity, ~100% now survive.

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Thromboprophylaxis

Pregnancy is a hypercoagulable state: consider need for thromboprophylaxis pre-pregnancy, at booking, throughout the antenatal period, at start of labour and once delivered. See below. For caesarean section

Thromboprophylaxis after vaginal delivery:

In all pregnant women avoid immobility and dehydration.

Risk factors: (Thrombophilia/past thromboembolism considered separately). Women with any two of the risk factors opposite (RED BOX):

Treatment: Treat with low molecular weight heparin (LMWH) eg enoxaparin starting as soon as possible after delivery (as long as no postpartum haemorrhage and ≥4h after epidural catheter siting or removal—6h if that was traumatic). Continue for 3–5 days even if at home. Dose of enoxaparin: if the early pregnancy weight (EPW) is 50–90kg, give 40mg/24h SC; if EPW <50kg, give 20mg/24h SC; if EPW >90kg give 40mg/12h SC. If heparin is contraindicated, use TED compression stockings (TED = transverse elastic graduated). For women with ≥3 persisting risk factors consider antenatal and postnatal prophylaxis, starting as early in pregnancy as possible as risk throughout. Continue normal dose prophylaxis when admitted in labour.

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Physiological changes in pregnancy

Hormonal changes

Progesterone, synthesized by the corpus luteum until 35 post-conception days and by the placenta mainly thereafter, it decreases smooth muscle excitability (uterus, gut, ureters) and raises body temperature. Oestrogens (90% oestriol) increase breast and nipple growth, water retention and protein synthesis. The maternal thyroid often enlarges due to increased colloid production. Thyroxine levels, see p 25. Pituitary secretion of prolactin rises throughout pregnancy. Maternal cortisol output is increased but unbound levels remain constant.

Genital changes

The 100g non-pregnant uterus weighs 1100g by term. Muscle hyperplasia occurs up to 20 weeks, with stretching after that. The cervix may develop ectropion (‘erosions’). Late in pregnancy cervical collagen reduces. Vaginal discharge increases due to cervical ectopy, cell desquamation, and ↑ mucus production from a vasocongested vagina.

Haemodynamic changes

Blood

From 10 weeks the plasma volume rises until 32 weeks when it is 3.8 litres (50% >non-pregnant). Red cell volume rises from 1.4 litres when non-pregnant to 1.64 litres at term if iron supplements not taken (↑18%), or 1.8 litres at term (↑30%) if supplements are taken—hence Hb falls due to dilution (physiological ‘anaemia’). WCC (mean 10.5 × 109/L), platelets, ESR (up 4-fold), cholesterol, β-globulin, and fibrinogen are raised. Albumin and gamma-globulin fall.

Cardiovascular

Cardiac output rises from 5 litres/min to 6.5–7 litres/min in the first 10 weeks by increasing stroke volume (10%) and pulse rate (by ~15 beats/min). Peripheral resistance falls (due to hormonal changes). BP, particularly diastolic, falls during the first and second trimesters by 10–20mmHg, then rises to non-pregnant levels by term. With increased venous distensibility, and raised venous pressure (as occurs with any pelvic mass), varicose veins may form. Vasodilatation and hypotension stimulates renin and angiotensin release—an important feature of BP regulation in pregnancy.

Other changes

Ventilation increases 40% (tidal volume rises from 500 to 700mL), the increased depth of breath being a progesterone effect. O2 consumption increases only 20%. Breathlessness is common as maternal PaCO2 is set lower to allow the fetus to offload CO2. Gut motility is reduced, resulting in constipation, delayed gastric emptying, and with a lax cardiac sphincter, heartburn. Renal size increases by ~1cm in length during pregnancy.

Frequency of micturition emerges early (glomerular filtration rate↑ by 60%), later from bladder pressure by the fetal head. The bladder muscle is lax but residual urine after micturition is not normally present. Skin pigmentation (eg in linea nigra, nipples, or as chloasma—brown patches of pigmentation seen especially on the face), palmar erythema, spider naevi, and striae are common. Hair shedding from the head is reduced in pregnancy but the extra hairs are shed in the puerperium.

Pregnancy tests

Positive eg from two weeks post-conception (or from the first day of the first missed period), until ~20 weeks of pregnancy, they remain positive for ~5 days after abortion or fetal death. Otherwise, the false +ve rate is low. They detect the Ã’-subunit of human chorionic gonadotrophin in early morning urine, so are positive in trophoblastic disease (p 264).

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Diabetes mellitus in pregnancy

Meticulous control around conception 'malformation rates. Tell all diabetics about preconception services; they must know before pregnancy. Preconception change to insulin may help control. Treat retinopathy pre-pregnancy. Up to 20% may develop proliferative retinopathy so screen twice in pregnancy. If severe renal involvement; avoid pregnancy. DM may be pre-existing or appear in pregnancy; glycosuria unrelated to DM is common (glomerular filtration ' and tubular glucose reabsorption'). Non-diabetic blood glucose levels in pregnancy are constant (3.5 4.5mmol/L) except after meals. Fetal glycaemia follows maternal, but compensatory fetal hyper-insulinaemia promotes fetal growth.

Complications

Maternal

Hydramnios (25% ?due to fetal polyuria), preterm labour (17% associated with hydramnios). Stillbirth near term was common.

Fetal

Malformation rates '3 4-fold. Sacral agenesis, almost exclusive to diabetic offspring, is rare (CNS & CVS malformations are much commoner). Babies may be macrosomic (too large) or sometimes growth restricted.

Neonatal risks

Hypoglycaemia, Ca2+', Mg2+', and RDS (p 118). They may be polycythaemic (29%) so more neonatal jaundice.

Antenatal care

Review in joint clinic with diabetologist. Confirm gestation with early ultrasound. Detailed abnormality scan at 19 20 weeks. Fetal echo at 22 weeks if early control poor. Educate about benefits of normoglycaemia and home glucose monitoring: regular postprandial monitoring does prevent harm to the baby. Insulin needs increase by 50 100% as pregnancy progresses so review regularly. Aim for fasting level <5.5mmol/L; 1h post-prandial level <7.5mmol/L. Give glucagon kit and ensure partner knows how to use it. Admit if adequate control impossible to achieve at home. Oral hypoglycaemics are currently avoided though glyburide does not cross placenta and may be safe.16

Monitor fetal growth and wellbeing by ultrasound and cardiotocography.

Delivery

Timing takes into account control of diabetes, any pre-eclampsia, maturity and size of the baby, and with attention to fetal wellbeing. Delivery before 38 weeks may result in neonatal respiratory distress. Deliver the baby where there are good neonatal facilities. Traditionally, delivery was at 36 38 weeks to avoid stillbirth; but with close supervision pregnancies may go nearer to (but not beyond) term.

In labour

Avoid acidosis and monitor the fetus (p 44). Avoid maternal hyperglycaemia (causes fetal hypoglycaemia). Monitor glucose; prevent hyperglycaemia with extra insulin (may need 5U/h) if β-sympathomimetics or glucocorticoids are used in preterm labour. Aim for vaginal delivery with a labour of <12h. Beware shoulder dystocia with macrosomic babies. With elective delivery, give normal insulin the evening before induction. During labour give 1L of 5 10% glucose/8h IVI with 1 2U insulin/h via a pump. Aim for a blood glucose of 4.5 5.5mmol/L (check hourly). Insulin needs fall as labour progresses and immediately postpartum. Stop infusions at delivery. Return to pre-pregnancy regimen. Do a caesarean section if labour is prolonged. Clamp cord early (as polycythaemia risk).

Postnatal

• Encourage breast feeding (oral hypoglycaemics contraindicated).
• Encourage pre-pregnancy counselling before next pregnancy (p 2) to transfer to insulin.
• Do a postpartum glucose tolerance test at 6 weeks.

Gestational diabetes

(OGTT glucose ‰ 7.8, OHCM p 294) Incidence: 3%.17 50% get full DM, so give lifelong dietary advice & follow-up.18 Equations exist for giving risk of post-pregnancy DM from pre-pregnancy BMI (p 530), fasting plasma glucose, and months since delivery.19 Other risk factors: age >30yrs; mothers who themselves have had low birth weights or IUGR (p 52); 1st-degree relative with DM; unexplained stillbirth;20 gestational DM before 27 weeks (or if needing insulin).21 22 [n=1636]

™£ Exercise, a good diet, and no smoking all help lower this risk.

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