Flow is defined as the amount of fluid, ordinarily blood, passing per unit time (usually per minute). Perfusion is defined as the volume of blood flowing through a mass of tissue per unit time. The standard measure of perfusion is millilitres of fluid per second per 100 g of tissue (or 100 ml in volume) i.e. the fractional blood volume in an area divided by the mean transit time through the area, where the area is scaled to a 100 ml of tissue. The fractional vascular volume is an index of the physiological vascularity of a region and represents the proportion of tissue occupied by blood. Several ultrasound based techniques have been used in an attempt to quantify perfusion. Vessel dimensions of capillaries and arterioles are below the spatial resolution of even the latest ultrasound machines, and capillary flow is slower than that required to generate a Doppler signal which leads to underestimation of true perfusion. For all ultrasound-based techniques movement artefacts are probably the greatest obstacle to obtain quantitative information on perfusion. This review will discuss the technology and use of the ultrasound mode of three dimensional power Doppler, its benefits and limitations in estimating vascularity focusing on the field of obstetrics.

Thyroid hormones are important in the development of the fetus and the placenta as well as in maintaining maternal wellbeing. Thyroid disorders are common in the population as a whole, particularly in women, and therefore are common during pregnancy and the puerperium. Biochemical derangement of thyroid function tests are present in approximately 2.5–5% of pregnant women.

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.

Eclampsia is defined in the obstetrical literature as the occurrence of unexplained seizure during pregnancy in a woman with preeclampsia. In the Western world, the incidence of eclampsia is ~1 per 2000 to 1 per 3000 pregnancies, but the incidence is 10-fold higher in tertiary referral centers and undeveloped countries where there is poor prenatal care, and in multi-fetal gestations. Nearly 1 in 50 women with eclampsia die as do 1 in 14 of their offspring, and mortality rates are considerably higher in undeveloped countries. Eclampsia is also associated with significant life-threatening complications, including neurological events. Seizure acutely can cause stroke, haemorrhage, oedema and brain herniation and thus lead to epilepsy and cognitive impairment later in life.

The Antiphospholipid syndrome (APS) is one of the current hot topics embracing rheumatology and obstetrics.

The first clinical description of APS was in 1983. Venous or arterial thrombosis, abortion and cerebral manifestations along with circulating antibodies were the first described hallmarks of the syndrome. In the following years other clinical features, which include pregnancy complications, such as recurrent miscarriages (RM), pre-eclampsia or severe placental insufficiency were described.

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.

Interest in the clinical associations between maternal intrapartum fever and adverse neonatal outcome has been longstanding, with publications of a relationship between maternal fever and cerebral palsy dating from the 1950s. Further recognition of the associations between either clinically or histologically characterised chorioamnionitis, ascending infection and neonatal wellbeing followed, with numerous reports in the 1960s and 70s, particularly as the neonatal significance of group B streptococcal infections became apparent. Similarly, with the systematic introduction of diagnostic light microscopy into clinical medicine, chorioamnionitis (inflammation of the placental membranes) and funisitis (inflammation of the umbilical cord) were recognised as distinct histological entities, with increasing recognition that the aetiology was likely to be infective. There are numerous texts discussing in detail the pathogenesis and histological features of chorioamnionitis and funisitis. The aim of this review is to provide an overview of the salient associated issues for clinical practitioners and to highlight areas of ongoing uncertainty and recent developments in understanding.

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.

Sepsis is associated with high morbidity and mortality worldwide. Although, it is not the major reason for intensive care unit admissions during pregnancy, several physiological changes that occur during pregnancy limit the ability of the pregnant woman to compensate for the derangements produced by severe sepsis, often resulting in severe organ dysfunction. Moreover, there are several disorders peculiar to the pregnant state, including preeclampsia, placental abruption, amniotic fluid embolism and postpartum haemorrhage, all of which can produce potentially life-threatening organ failure and may be present concurrently with sepsis contributing to maternal mortality. Evidence-based guidelines advocate assessment and monitoring aimed at early recognition and treatment of sepsis. Early goal-directed therapy, adequate blood glucose control, and corticosteroid replacement when indicated are improving outcomes in patients with severe sepsis, although most of these have not been validated in pregnancy.

Premature rupture of membranes (PROM) is a major cause of perinatal mortality and morbidity associated with preterm delivery in a third of cases. Fetal survival is even more compromised when the membranes rupture early in the second trimester (very early PROM). Survival is associated with problems of delivery of the very preterm fetus as well as associated risks of feto-maternal infection. In the context of studies of amnioinfusion, very early rupture of membranes is defined as rupture between 16 and 26 weeks of pregnancy.

Screening for Down syndrome is an important part of routine antenatal care and should be made available, if requested, after appropriate counselling including risks and benefits, to all pregnant women, regardless of maternal age. Prenatal screening for fetal Down syndrome and other aneuploidies has advanced significantly since its advent in the 1980s. Historically, women 35 years or older were offered prenatal genetic counselling and the option of a diagnostic test such as chorionic villus sampling or amniocentesis. With this screening approach only 20% to 30% of the fetal Down syndrome population are detected antenatally. Sonographic and maternal biochemical markers are now used in combination to screen for aneuploidies in the first and second trimesters. The most common screening method in the first trimester combines the maternal serum markers HCG and PAPP-A with the sonographic evaluation of fetal nuchal translucency thickness. Newer markers have been proposed to further refine the risk assessment for Down syndrome to maximise detection rates and minimise false positive rates. These newer first trimester markers include sonographic assessment of the fetal nasal bone (NB), the frontomaxillary facial (FMF) angle, ductus venosus (DV) Doppler and tricuspid valve regurgitation (TR).

Physiologic changes in maternal haemodynamics, hormones and autonomic properties contribute to arrhythmias in pregnancy. While arrhythmias most commonly occur in pregnant women with structural heart disease or those with a history of cardiac arrhythmias, they can also occur de novo in women with no documented cardiac disease.

Platelets are an essential component of the first step in the process of haemostasis, plugging defects in the endothelium and providing a surface for secondary haemostasis to occur, via the coagulation pathway. Platelet aggregation and activation cause granule release of von Willebrand factor, ADP and serotonin, which, in turn, results in recruitment of more platelets to form the platelet plug. This serves to stop the bleeding, and also to activate the coagulation pathway on the surface of the activated platelets, leading to a firm fibrin clot.

The most common maternal risk factor associated with neonatal complications during delivery is obesity. Although gestational diabetes mellitus (GDM) occurs in 5–10% of the pregnant population, obesity, by virtue of its prevalence, far outpaces GDM as the most important underlying risk factor for increased fetal adiposity. The mechanisms underlying maternal insulin resistance may play an important role in the diversion of excess fuels to the fetus. Maternal adipose depots increase in early pregnancy, followed by increased adipose tissue lipolysis and subsequent hyperlipidaemia, which mainly corresponds to increased triglyceride levels (TG). A positive correlation between maternal TG and infant body weight or fat mass has been found in both GDM and non-GDM obese women. Increased oxidative stress, altered adipokines, and inflammatory cytokines have also been found in obese pregnant women, suggesting an adverse metabolic outcome even in normoglycemic conditions.

At the end of 2007, Time magazine listed the “benefits of vitamin D” as one of its top 10 medical breakthroughs for that year. Since then there has been a remarkable upsurge of interest in vitamin D, with new research advances seemingly published on a weekly basis. In particular, there has been increasing awareness of the variability of vitamin D status in populations across the globe and, significantly, a growing debate about the need for revised parameters for vitamin D supplementation. Although sub-optimal vitamin D is likely to be a widespread problem for 21st century societies, it is also clear that some groups are at much greater risk of low vitamin D status. Prominent amongst these are pregnant women and the aim of the following review article will be to discuss this problem in further detail with specific emphasis on its potential physiological and clinical impact.