Insights from outside BJOG

It is generally thought that coffee consumption should be limited in pregnancy because studies have linked high intake to fetal growth restriction. However, there are areas where reported ‘cups of coffee drunk’ may not accurately reflect caffeine effects because of recall, coffee types and choices, as well as questions about the precision of fetal anthropometric measurements. The National Institute of Child Health & Human Development study group sought to avoid such variables by recruiting 2000 non-smoking healthy women representative of the United States population and corroborating their declared coffee intake with caffeine levels and relating these to precise measures of fetal growth (Gleason et al. JAMA Netw Open 2021;4:e213238). Singleton neonates with a mean gestational age of 39.2 weeks formed the cohort whose measurements of weight, length, head, arm and thigh circumference were correlated with maternal plasma caffeine levels at the end of the first trimester. There were small but significant differences in growth between those infants whose mothers were on the first and fourth quantities of caffeine levels – for example, lower birth weight by a mean of 85 g, length 0.4 cm and head circumference 0.3 cm. The outcomes were consistent across all measurement domains. Most O&G Colleges recommend that pregnant women restrict their coffee consumption to less than 200 mg of caffeine per day – one cup. Data from the above study suggests a continuum of effects such that there may be no lower level that is safe. They even tested for known ‘fast versus slow’ genetic caffeine metabolisers and found no difference. Unlike in non-pregnant individuals where up to six cups of coffee per day has benefit, pregnancy may be a time to reduce intake to zero. Caesarean delivery and neurodevelopment