The aetiology of hypoplastic left heart syndrome (HLH) is complex and involves both genetic and environmental factors. Hypoplastic left heart syndrome accounts for 1.4–3.8% of all congenital heart defects but up to 25% of neonatal deaths. As well as having a high mortality, HLH is a very significant cause of morbidity and therefore justifies aetiological investigation.

Immunology is a fast developing and intriguing biomedical science, which can give rise to specific considerations about the physiological process of both successful and unsuccessful vivparous pregnancy. It is normal in clinical organ transplantation for unmatched foreign tissues (allografts) to provoke immunological rejection by the host, unless there has been prior tissue matching (histocompatibility antigen tissue typing) or immunosuppressive therapy. Thus, it is still not fully clear how, after ‘random’ mating, haplo-nonidentical fetal tissue is able to survive in the potentially hostile immunocompetent maternal environment. The majority of pregnancies survive uninterrupted and there has now been much speculation and research regarding the immunological success of pregnancy (i.e. nature’s transplant). Medawar orginally offered four nonexclusive hypotheses to explain the enigmatic immunological survival of normal pregnancy:

1) the conceptus is not immunogenic and therefore does not evoke an immunological response;

2) pregnancy alters the maternal immune response;

3) the uterus is an immunologically privileged site;

4) the placenta is an immunological barrier between the mother and the as yet immunologically incompetent fetus.

Before discussing these, as well as some of the clinical immunological problems that may arise during pregnancy, it is necessary to outline some of the basic components of the normal immune system. This will lead to a description of current understanding of immunological events at the fetomaternal interface as well as the maternal immune response in human pregnancy.

Mechanical heart valves pose a particular challenge in pregnancy, as the primary agent used to prevent valve thrombosis, coumadin (warfarin), is a known teratogen. Alternatives to coumadin, such as unfractionated heparin (UFH) and low-molecular weight heparin (LMWH) are safer for the fetus, particularly during the first trimester of pregnancy, but expose the mother to potential valve failure. This review will examine these controversies and the complex literature regarding management in pregnancy.

Diagnostic ultrasonography has achieved an almost universal role in the practice of obstetrics, due to technological improvements in equipment and the experience acquired by well-trained ultrasonographers. Within the general population, over 3% of children reportedly have major congenital malformations that are life-threatening, require major surgery or have serious cosmetic effects. Many of these malformations can be detected antenatally by obstetric ultrasound. The introduction of high frequency transvaginal ultrasonography is a major development in the area of obstetric ultrasonography. Using this method, fetal anomalies have been successfully identified as early as the first trimester of pregnancy, leading some investigators to advocate routine ultrasound examination during pregnancy in order to screen for fetal anomalies at a gestational age that permits consistently accurate diagnosis and maximizes parental choice.

Despite advances in both obstetrics and neonatology the perinatal mortality rate (PNMR) among twins still remains high, estimated as accounting for approximately 10% of all perinatal mortality. Perinatal mortality rates (PNMR) for England and Wales showed a dramatic reduction in perinatal deaths for multiple births over the 1950s to 1980s with a fall from approximately 90 to less than 50 per 1000 births. The Northern Region Perinatal Mortality Survey Steering Group also reported a significant reduction in twin PNMR between 1982 and 1994 from 55.4 to 44.4/1000 births. A similar decrease has also been noted in the Japanese twin population with a reduction in the PNMR between 1980 and 1998 from 91 per 1000 births to 31 per 1000. In Scotland between 1986 and 1990 PNMR for twins was 47 per 1000 approximately 4-5 times the rate in the singleton population. The higher preterm delivery rate in twins, either from spontaneous or induced labour, with its associated problems of prematurity remains the major cause of morbidity and mortality. Other factors, which contribute to the higher PNMR in twins include fetal growth retardation, intra-twin birth weight discordancy, fetal anomalies and problems specific to monochorionic twin gestations.

Hydrocephalus is a pathological increase in intracranial cerebrospinal fluid, usually within the lateral ventricles and often, although not always, associated with an increase in intracranial pressure and an abnormally large biparietal diameter. Ventriculomegaly simply means enlargement of the lateral cerebral ventricles. The reported incidence of hydrocephalus at birth is 0.5–3 per 1000. The incidence of ventriculomegaly diagnosed antenatally by ultrasound (atrium 10–15mm), varies from 1.48 per 1000 (8/5400) to 22 per 1000 (11/500), the latter study being in a low risk population.

In 1981 De Bold and colleagues demonstrated that when extracts of atrial tissue were given intravenously to rats a large diuresis and natriuresis occured promptly. The structure of the hormone concerned, atrial natriuretic peptide (ANP), was elucidated in 1983. Since then, ANP has received attention as a potentially important mediator in the homoeostasis of sodium and fluid volume.

Routine electronic fetal heart rate monitoring has been associated with a significant reduction in fetal mortality and early onset neonatal seizures. However, the positive predictive value of changes in the fetal heart rate pattern is very low, and thus there has been a disproportionate increase in the rates of operative intervention in labour, compared with very modest reductions in neonatal encephalopathy. Recent studies have demonstrated that postasphyxial encephalopathy in term babies now derives almost entirely from low and medium risk pregnancies. This suggests that the current model of obstetric care is very effective in high-risk populations. However, further improvements in the care of what are now generally low risk patients will require simple, widely applicable strategies for detecting the infant at risk of asphyxial complications.

It is now 21 years since active management of labour was first reported in the British Medical Journal. Whether one agrees with Professor O'Driscoll or not, there is little argument that his views on the care of women in labour have had a major impact on obstetrics worldwide. As active management comes of age, it is appropriate to review the literature on this subject.

The haemoglobin disorders are a group of recessively inherited conditions of varying severity. In the homozygous state, alpha zero thalassaemia causes hydrops fetalis, beta thalassaemia usually causes a severe transfusion-dependent anaemia and sickle cell anaemia (HbSS), haemoglobin S/C disease, haemoglobin S/D disease and haemoglobin S/beta thalassaemia cause sickling disorders ranging from quite mild to very severe. Haemoglobin disorders are among the commonest inherited diseases in the UK. Management can be very burdensome, but produces good results in many cases. The disorders can also be prevented by a programme of carrier screening, genetic counselling and prenatal diagnosis in populations at risk. The WHO has defined a “haemoglobinopathy control programme” as an integral strategy combining optimal patient care with prevention based on community education, propective carrier diagnosis, genetic counselling and the offer of prenatal diagnosis. The services required for haemoglobin disorders in the UK have recently been reviewed in a report from the Standing Medical Advisory Committee of the Department of Health. This report focuses on genetic counselling and prenatal diagnosis for haemoglobin disorders.

A baby may be small for a variety of reasons, but there are certain overt maternal and fetal factors which may lead to, or are associated with, a poor fetal growth rate. Pre-eminent amongst the maternal factors is severe pre-eclampsia and in women with this disease the smallness of the baby is almost certainly due to the inadequacy of the uteroplacental circulation. Other maternal factors of importance are cigarette smoking, drug abuse and certain infections such as malaria. The most obvious fetal factors associated with a low birth weight are congenital malformations and chromosomal abnormalities, and there the failure of the fetus to achieve a normal weight is clearly an expression of a generalised disorder of growth and is unrelated to the adequacy or otherwise of the placenta. If cases such as these are removed from consideration, there remains an important residue of unduly small infants who are delivered after an apparently uncomplicated pregnancy, are free from congenital malformations and have a normal karotype; it is this group which is considered here.

Pre-eclampsia (PE) remains the leading cause of maternal and fetal mortality in the developed world and parts of the developing world. Morbidity and mortality from PE is increased in the developing world compared to the developed world, as availability and access to antenatal care and pathology services are limited.

Ancient Egyptian medical papyri (1550BC) emphasised diagnosis by examination as the cornerstone of the decision to treat or not to treat an ailment. Today the information about the likelihood of diagnosis (and related prognosis) that interventions purport to treat comes from a combination of tests as shown in Figure 1. In addition to easy-to-obtain history (risk factors and symptoms) and examination (signs), current testing includes sophisticated investigations (haematology, biochemistry, radiology, microbiology, etc), which can also be invasive and expensive. Obstetricians routinely incorporate many test results into decision-making concerning management of women at risk of preterm birth, but studies to examine the ways in which even a small number of these tests alter the benefit and harm of treatments are rare.

The newborn baby draws its first postnatal breath either during or within seconds of delivery. Within minutes, a regular breathing rhythm is established and this remains virtually continuous for the remainder of postnatal life. The mechanisms responsible for these sudden, dramatic and vital changes in the respiratory system at birth are only partially understood. Since fetuses make intermittent breathing movements long before birth, understanding the control of the fetal respiratory system may be essential to understanding the rapid onset of respiratory efforts at delivery. In this review the stimuli present at birth will be considered and, based on our current understanding of the fetal and neonatal respiratory control systems, those factors which are likely to play an important role in the initiation of lung ventilation at this time will be examined. Normal respiratory events in the early postnatal period will be concentrated on, but it is important to recognize that in some cases problems occur: a neonate may fail to initiate breathing efforts rapidly, or an apparently healthy premature neonate may suddenly stop breathing a few days after birth. In both cases, clinical intervention may be required to maintain adequate gas exchange and to prevent brain damage or death. Clearly, greater knowledge of respiratory control during this critical time of life would assist in the development of more appropriate and successful treatments for these life-threatening disorders.

This paper presents a review of decision making in obstetrics. The first section deals with the obstetric problem-solving model, the second general decision theory and finally several aspects of decision making in the domain of obstetrics are examined.

During pregnancy and lactation there are many changes in maternal calcium physiology which maintain homeostasis in the face of greatly altered calcium balance. In the course of fetal growth and development, 30g of calcium is incorporated into the fetus by term, an amount derived wholly from the maternal system. Most of this accumulates in the latter half of pregnancy, representing a net transfer of 200mg calcium/day (5mmoles). The fact that this is not achieved at the expense of the maternal skeleton is testimony to the conservative and protective adjustments that are seen in calcium metabolism in pregnancy. Furthermore, the changes must persist both in the puerperium and later when lactation presents a source of continuing maternal calcium loss to the suckling infant. The calcium content of human breast milk s i 6–9mmols calcium/l, two to three times the maternal serum level. In the course of one week a normal breast-fed at term infant takes two to three litres of milk, containing 10–30mmols of calcium. The maternal daily calcium intake recommended by the World Health Organization s i 1.25g (30mmol) of which only 25% is absorbed. Thus calcium loss from mother to baby is significant and may not be replaced by diet in many parts of the world.

Attwood traces the earliest possible description of a case of amniotic fluid embolism (AFE) to 1825. The next case was described by Meyer some 101 years later. Not until 1941 was this obstetric catastrophe recognised as constituting a true syndrome with its own clinical and pathological characteristics. Any combination of sudden and profound shock, dyspnoea, cyanosis, apprehension, seizures, and the failure of rapid blood coagulation may herald the clinical onset of an AFE. Liban was the first to report the detection of squamous cells throughout the systemic circulation, an observation which was not explained at the time. Many have commented upon the ominous fetal heart pattern that almost invariably accompanies AFE if the fetus is in-utero at the time of the embolus.