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.

It is well recognised that birth before 32 weeks of gestation is associated with substantial neonatal morbidity and mortality and these risks have been extensively reported. The focus of perinatal research for many years has therefore been very preterm and extremely preterm delivery, since the likelihood and severity of adverse neonatal outcomes are highest within this group. In contrast, until recently, more mature preterm infants have been understudied and indeed, almost ignored by researchers.

Umbilical cord prolapse is the descent of the umbilical cord through the cervix alongside (occult) or past (overt) the presenting part in the presence of ruptured membranes. Cord prolapse is a rare obstetric complication, usually requiring immediate delivery of the fetus to reduce neonatal morbidity and mortality. Therefore staff caring for women in labour should train regularly to manage it appropriately, because team training has been demonstrated to improve outcomes.

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.