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What are the implications of first trimester fetal growth and racial origin?
Two of the greatest challenges facing reproductive science in many developed countries are dealt with by two studies in this week's BMJ.1 2 The first challenge is the need to find innovative approaches to prevent perinatal death, low birth weight, and preterm birth. The second is the challenge to our healthcare systems resulting from the attendance of large numbers of people of differing racial origins. Together, the findings from these two studies provide vital clues as to how healthcare outcomes may be improved by strategies aimed at the early stages of human life.
In the developed world, the outcome of pregnancy for both mother and child improved dramatically during the 20th century. Reproduction has never been as safe as it is today. Many of the advances that have contributed to improved outcomes have come from the application of medical discoveries in late pregnancy and during childbirth. Yet some of the major complications of pregnancy are proving remarkably difficult to prevent. Several of the major causes of perinatal mortality are not declining, including term deaths from hypoxia and infection,3 and rates of preterm birth in most countries are either static or rising.4 Furthermore, in multiracial communities, different racial groups often show disparities in outcomes, despite the apparent availability of high quality healthcare services for all.5 It may be that current systems of care will be unable to improve poor outcomes until innovative approaches to prediction and prevention are discovered.
In this week's BMJ, Bukowski and colleagues1 show that reduced fetal growth in the first 12 weeks of pregnancy contributes to low birth weight and early birth. Their study was based on women who had known dates of conception through assisted reproductive technology, and it paves the way for improved prediction of the outcome of pregnancy by incorporating data from the first trimester.
Recently, it has been reported that low levels of placental proteins, such as pregnancy associated plasma protein A, around the time of first trimester screening may predict subsequent fetal growth restriction.6 Evaluation of early fetal growth patterns may add to this predictive ability. Bukowski and colleagues' findings also add a new dimension to our understanding of the early origins of adult health and disease. Low birth weight is associated with adult illnesses, including heart disease and diabetes, and much of the early evidence for this association came from midwifery records in the United Kingdom.7 Emphasis on birth weight resulted from its ready availability in medical records, but more recent research has attempted to unravel the patterns of fetal growth rather than rely on the summary measure of birth weight.8 The evidence that growth in the first trimester may predict subsequent pregnancy outcomes suggests that measurable events in the first trimester may play a greater role in determining our destiny than previously thought.
Also in this week's BMJ, Balchin and colleagues2 show that racial origin influences the risk of perinatal mortality at different gestational ages. The study follows a previous report by this group that median gestational age at delivery is lower in South Asian and black women than in white women.9 After 40 weeks, antepartum stillbirth rates increased at earlier gestational ages in South Asian women.2 This finding suggests that in this racial group it might be prudent to start fetal surveillance and planned delivery at an earlier gestational age than is the current standard of practice, which was developed using data from pregnancies of white women.
The findings may also be another milestone in our journey from health care that assumes all patients are fundamentally the same to an era where a variety of individual attributes may be harnessed to maximise the effectiveness of evidence based care.10 Furthermore, the evidence that racial origin may be important in the management of pregnancy emphasises that research should be conducted within specific communities so that tailored management protocols can be devised.
People of South Asian origin are one of the groups most at risk in the current epidemic of obesity, diabetes, and metabolic syndrome.11 Much of this risk arises from rapid transition from traditional to Westernised lifestyles, with a mismatch between the metabolic world for which the offspring is intended and the life that actually ensues.12 At the heart of this sequence is low birth weight, followed by accelerated postnatal growth. Research is now needed to investigate how early in gestation such growth restriction occurs, and if biometry in the first trimester can be of use in predicting predisposition to chronic disease in adulthood.
Competing interests: None declared.
Provenance and peer review: Commissioned; not externally peer reviewed.