Most perinatal deaths occur in normally formed, normally grown babies weighing >2.5 kg, as the result of birth trauma and asphyxia related to CPD, pre-eclampsia, abruption, cord prolapse, and malpresentation. These deaths are much more preventable than those from prematurity and IUGR.
Babies who are sufficiently small to be classified as being of low birthweight (<2500 g) may: (1) have been born after a pregnancy which was abnormally short, or (2) have grown abnormally slowly during a pregnancy of normal length. These ‘small for dates’ babies suffer from intrauterine growth retardation (IUGR). In the developing world 25% of babies may be low birthweight, and of these 70% may have IUGR. Its causes in approximate order of frequency include: malnutrition, placental malaria, HIV disease, gestational hypertension, essential hypertension, recurrent antepartum haemorrhage, sickle-cell disease, malformations and chromosome abnormalities, other virus infections, smoking, and alcohol. There is also an ‘idiopathic’ group (30% in the developed world) in whom there is no obvious cause, but who are generally considered to be suffering from uteroplacental vascular insufficiency. A hungry starving baby from any of these causes readily dies, particularly during early labour, when his heart suddenly stops.
Because of the overwhelming importance of malnutrition as a cause, 21 of the 22 million low birthweight babies who are born each year are in the developing world. Their chances of dying are 20 times higher than those of other babies. Malnutrition is also the most potentially preventable cause.
IUGR is not easy to detect clinically. The risk factors for it, some of which are determined by malnutrition, include: (1) IUGR in previous pregnancies. (2) Low weight before pregnancy began. (3) Low weight-gain during pregnancy. (4) Multiple pregnancy. (5) Smoking. Even so, 30%–50% of cases commonly remain undiagnosed. The only way ? ultrasound you have of diagnosing IUGR is to encourage your midwives to measure the fundal height as carefully as they can between 20 and 36 weeks. If the uterus is 5 cm lower than it should be, and there are <10 movements in 12 hours, you can diagnose IUGR.
Unfortunately, many mothers are unsure of their dates, and most health workers (including doctors) are unable to record the height of the fundus with sufficient accuracy. Even if we can, it is of little value in multiple pregnancy, polyhydramnios, a transverse lie, or in a very obese mother.
The fundal height chart (23-15) is derived from UK. If low birthweight babies are common in your district, you will find many mothers falling below the 10th centile, either because their babies have IUGR or because they are genetically small (the relative importance of these factors is unknown).
If you diagnose IUGR during pregnancy, and decide to deliver a mother before term (it is not one of the indications for induction in Section 19.3), don’t do so before 34 weeks. Do the surfactant test (23.1), in case her dates are wrong. You then have a choice between inducing labour (23.2) and elective Caesarean section (22.11). Babies with IUGR tolerate asphyxia badly.
Babies with IUGR born at term have only a slightly increased risk of a major handicap, such as cerebral palsy or mental retardation. But between 1% and 30% of them have some minimal cerebral dysfunction, such as problems with speech, language, and learning. The babies at greatest risk of some major handicap associated with IUGR, particularly cerebral palsy, are: (1) The badly asphyxiated baby with severe IUGR born at or past term. (2) The baby with IUGR delivered <34 weeks. Try to diagnose and deliver babies in the ‘window’ between 34 and 36 weeks—if you can. Delivering a baby whose mother has diabetes (21.2) presents similar problems in judging the best time for delivery, the main difference being that he is too big rather than too small.
Much of the effort of modern obstetrics is devoted to detecting babies with IUGR, monitoring them, and getting them out into the world at just the right moment, when the risks outside the uterus are less than those inside it. If the moment of induction can be judged successfully, it may increase a child’s chance of survival. Unfortunately, despite a massive investment in resources, a baby suspected of having IUGR is often found to be normal, and vice versa. It is thus not surprising that IUGR is seldom diagnosed in the district hospitals of the developing world, and even with the sophisticated technology of the industrial world, the diagnosis is often wrong. However, you can treat the more manageable causes of perinatal mortality, some of which express themselves as IUGR—malaria, gestational hypertension, syphilis, obstructed labour, and poorly managed breech and twin deliveries. HIV however remains a huge challenge.