Given the phylogenic antiquity of the renin angiotensin system (RAS) and the high degree of renin gene sequence conservation between species, it is perhaps not surprising that the RAS should be central to cardiovascular homeostasis. Nor, given the common embryological origin of the kidneys and reproductive tracts, is it especially surprising that the system should be influenced by, and may itself influence, the state of pregnancy. In this review I shall attempt to give an outline of the workings of the system in normal and in hypertensive pregnancy. The RAS is now known to be involved in spheres far beyond the ‘simple’ control of sodium and water homeostasis, and hence of blood pressure. Its roles in reproduction and in fetal life in animals have been very recently reviewed; this review will therefore confine itself to human studies unless otherwise stated.

We cannot talk to the fetus. Our ability to place the fetal condition accurately in context, therefore, lies with indirect evidence and inferred responses. We can examine the fetus. We can do so in a most comprehensive fashion, addressing the salient points of fetal anatomy, both structural and functional. We are able to perform routine evaluation of every system and the methodology is available to assess critical areas such as the heart and the central nervous system in specific detail.

Advances in both imaging techniques and in treatments for immune thrombocytopenias affecting the fetus have allowed for more accurate antenatal predictions of severe disease and effective antenatal treatments for those fetuses who are at risk of sequelae. This article will review current knowledge of the diagnosis and treatment of affected fetuses in alloimmune thrombocytopenia and in immune thrombocytopenic purpura.

The historical background of post partum haemorrhage (PPH) dates back to the 17th century. William Smelley published his famous treatise of the theory and practice of midwifery in 1752. His observations sent a clear message to practitioners of the time that haemorrhage in midwifery can be a messenger of death.

Current hypotheses regarding the origins of preeclampsia have focused on the “Two stage model”. This model suggests that the primary steps in the pathophysiologic sequence of preeclampsia are initiated by abnormal placentation including the classic finding of abnormal trophoblast invasion of maternal decidual spiral arteries. The second stage of the sequence includes the elaboration of a single or multiple substances from these disordered placentas which contribute to the generalized maternal systemic illness, eventually manifesting as endothelial injury, hypertension and proteinuria. Recent studies have focused on the role of pro and anti-angiogenic peptides as potential placentally derived aetiologic agents in this pathophysiologic sequence, although other placental products have been highlighted in recent research. Despite the fact that this modeling of preeclampsia has widespread support significant limitations to this hypothesis can be identified.

Cardiac and respiratory systems undergo significant changes in pregnancy and the puerperium, and the course of disease of these two systems in pregnancy can be difficult to predict and manage. Good assessment and planning is essential for the general management of patients with cardiorespiratory disease and will directly impact on the anaesthetic services they require and receive.

Congenital cytomegalovirus (CMV) infection is now the commonest infective cause of neurological handicap. Arguably, there is no other single contributor to developmental disability where a greater opportunity, and imperative, exists to improve outcomes than CMV. CMV is the most common intrauterine infection and congenital CMV is the leading non-inherited cause of sensorineural deafness. The public health impact of CMV is significant: the overall birth prevalence of congenital CMV is estimated at 0.64%, with 11% of live born infants displaying symptoms.

Hypoxia in pregnancy is rare, however the anatomical and physiological changes associated with pregnancy may exacerbate hypoxia and hypoxaemia arising from pathological processes.

In this review we seek to briefly outline the well recognised changes to the maternal airway and respiratory anatomy and physiology. We will discuss a hierarchical approach to the tests used in differential diagnoses, summarise the physical principles behind commonly used tests and identify pitfalls and considerations in their use in the obstetric population. Some of the more commonly seen pathological states that may cause hypoxia in pregnancy will be discussed.

The last century has seen dramatic developments in medical care as technological advances have been applied to both diagnosis and treatment. Some areas of obstetrics have been slow to benefit from these advances – and none more so than the care of the fetus in labour.

Some half a million women die annually across the world from causes related to pregnancy and childbirth. Approximately one-quarter of these deaths are caused by complications of the third stage of labour, mainly postpartum haemorrhage (PPH). In the developing world, the risk of maternal death from PPH is approximately one in 1000 deliveries. In the United Kingdom the risk of maternal death from obstetric haemorrhage is about 0.39 in 100000 deliveries.

Obesity is a growing problem in obstetric practice. A recent study from Glasgow (UK) showed that 50% of women of childbearing age are either overweight (Body Mass Index [BMI] = 24.9–29.9kg/m2) or obese with 18% starting pregnancy as obese. Obesity prevalence has doubled over a decade from the early 1990’s. In the US it is estimated that 30% of reproductive-age women have a BMI greater than 30 kg/m while 7% have a BMI > 40 kg/m2. A recent report from the UK found that 5% of women had a BMI >35 kg/m2, 2% > 40 kg/m2 and 0.2% >50 kg/m2 with an association not only with social deprivation, but also with a higher prevalence of pre-existing medical disorders such as diabetes and hypertension and medical complications of pregnancy such as preeclampsia. Obesity was also associated with increased rates of macrosomia, operative delivery and postpartum haemorrhage. These data highlight the fact that obesity is an increasing health concern particularly in young women of childbearing age. Obesity will expose them to significant pregnancy complications ranging from miscarriage and fetal abnormality through to operative delivery and thromboembolism. There are also challenges for the delivery of maternity care to meet the needs of these women. As obesity is associated with significant pregnancy complications it is important that women enter pregnancy with an optimum body weight. Many complications, such as fetal abnormality occur in the first trimester and so pre-pregnancy weight reduction is preferred. Further, there is insufficient evidence to recommend specific dietary and/or physical activity interventions to reduce weight or moderate weight gain during pregnancy.

Subspecialization in fetal medicine has expanded the scope for obstetricians to investigate the fetus and its surrounding environment in greater detail. Of the advances in technology that have made this possible, ultrasonography is the most important. A high degree of skill is required if it is to be applied to the performance of invasive diagnostic techniques. These should be performed only in specialized centres with appropriate facilities and an adequate referral base. However, it is important for obstetricians to know what is possible in the field of prenatal diagnosis and therapy in order to give patients the best advice.

The childhood effects of antenatal exposure to cocaine are largely unknown. While several authors have evaluated the consequences of antenatal cocaine exposure during the neonatal period and early childhood, there are no large, blinded and systematic studies of the effects beyond early childhood and no data at early school age.

Hepatitis B and its complications are one of the major global health problems. Around 2 billion individuals are infected by hepatitis B virus (HBV) worldwide, more than 350 million are chronically infected, and approximately 15 to 40 percents of them will develop serious complications such as liver cirrhosis, hepatic failure, or hepatocellular carcinoma (HCC). The worldwide prevalence of chronic HBV infection ranges from 0.1 to 20 percent and varies widely in different geographic areas. According to the prevalence rate, WHO has classified countries into 3 levels: high areas (>8%) such as Africa, Asia, Western Pacific and Middle East; intermediate areas (2–8%) such as South America and Eastern Europe, and low areas (<2%) such as Western Europe, North America, and Australia.

Polycystic ovary syndrome (PCOS) is a common hormonal disorder affecting around 5–8% of women of reproductive age. It has a variable clinical spectrum including hyperandrogenism, menstrual abnormalities, polycystic ovaries and metabolic features like diabetes mellitus, obesity and dyslipidaemia. The manifestation of PCOS and its impact especially on reproductive function and pregnancy are profoundly affected by associated features of obesity/raised body mass index and metabolic syndrome.

The uterine cervix is a remarkable structure, which plays an essential role in pregnancy. During the development of the conceptus within the uterus, the cervix usually remains firmly closed to ensure that the developing fetus attains an appropriate degree of maturity to permit extra-uterine survival. On the other hand, it prepares for labour and birth, by undergoing a process of effacement, whereby the substance of the cervix shortens and thins out. During labour, it must be stretched and dilated to a sufficient diameter, usually about 10cm at term, to allow the successful passage of the fetus through the birth canal.

Successful human pregnancy is associated with striking physiological changes. Plasma volume increases early in the first trimester, attaining maximal expansion near term, when the increment above non-pregnant values is about 1.5 L (50–60%), and is a contributory factor in maintaining organ perfusion in the presence of arteriolar and venous dilatation. Effective renal plasma flow (ERPF) and glomerular filtration rate (GFR) increase to values 50–70% above non-pregnant levels by term. There are also gestational alterations in osmoregulation as well as in the renal handling of sodium, potassium and glucose, coincident with altered tubular function. Plasma volume expansion is significantly related to fetal growth and pregnancies complicated by intrauterine growth retardation and pre-eclampsia are associated with reduced plasma volume and impaired renal function. Elucidation of factors involved in volume homeostasis and renal function in pregnancy is therefore of clinical as well as physiological importance. Atrial natriuretic peptide (ANP) causes vasodilatation, natriuresis and inhibition of the renin-angiotensin system and is clearly an important factor in volume homeostasis and renal function.

Asthma is the most common significant chronic medical condition affecting young adults and it is therefore often encountered in pregnancy. Approximately 3% of women of child-bearing age suffer some degree of asthma and this prevalence is increasing. Some of the apparent increase is due to heightened awareness of the condition, although air pollution and increased childhood exposure to house dust mite may also be contributing.

Holoprosencephaly (HPE) is an uncommon and clinically severe abnormality of forebrain development, resulting from failure of septation, or cleavage, of the midline forebrain structures. It encompasses a range of brain pathology classified as lobar, semilobar or alobar HPE reflecting increasing degrees of failed septation. The closely related development of the mid-face area is frequently disturbed, with coexisting facial phenotypes ranging from cyclopia to normal.

Preeclampsia (PE) is a multisystem disorder of human pregnancy, affecting about 6% of all pregnancies worldwide, and is one of the leading causes of maternal and infant morbidity and mortality. Despite decades of research into the pathogenesis of this complex disease, the underlying mechanisms remain unclear. As a result, the options for prevention and management of PE are limited. In recent years, there has been a growing body of evidence suggesting that folate deficiency is associated with PE, and folic acid supplementation may reduce the risk of developing PE in certain populations. Folate contributes to cell division and growth, and folate metabolism is involved in a large number of physiological and pathophysiological processes in human development. Sufficient supply of folate is therefore particularly important during pregnancy. Nevertheless, the exact mechanisms of folic acid deficiency increasing the risk of developing PE are still unclear. This article reviews what is understood about the aetiology of PE and the relationship between folate metabolism and PE so as to enhance further discussions on the subject.