OS027. Ethnicity and adverse pregnancy outcomes: A cohort study.

Introduction: Women who develop pregnancy complications are more likely to develop cardiovascular disorders later in life. A history of pre-eclampsia (PE) is associated with a four-fold increased risk of hypertension and twice the risk of future ischaemic heart disease and stroke. Early identification of women at risk of developing pregnancy complications is likely to facilitate targeted antenatal surveillance and possibly intervention. Maternal ethnicity affects the risk of developing some of these complications, and so is likely to be an important variable in the risk assessment.

Objectives: The main aim of this study was to quantify the ethnicity-related risk of adverse pregnancy outcomes.

Methods: This was a multicentre cohort study in singleton pregnancies at 11(+0)-13(+6) weeks of gestation. Data on maternal characteristics, medical and obstetric history were collected and pregnancy outcomes ascertained. Racial origin was classified into Caucasian, African, South Asian, East Asian and mixed. The adverse pregnancy outcomes in this study included PE, gestational hypertension (GH), gestational diabetes (GDM), preterm delivery (PTD), small for gestational age (SGA), large for gestational age (LGA), stillbirth, obstetric cholestasis (OC) and emergency Caesarean section (CS). The diagnosis of PE and GH was made according to the guidelines of the International Society for the Study of Hypertension in Pregnancy. The neonate was considered SGA if the birthweight was less than the 5th percentile and LGA if the birthweight was more than the 90th percentile for gestation at delivery. The diagnosis of GDM was made if the fasting plasma glucose level was at least 6mmol/L or the plasma glucose level 2h after oral administration of 75g glucose was 7.8mmol/L or more (WHO). Stillbirth was defined as the death of a fetus before birth after the 24th week of pregnancy. The diagnosis of OC was made when there was pruritus in association with abnormal liver function in the absence of any other identifiable liver pathology which resolved after delivery. Multiple regression analysis was used to examine which maternal characteristics provided a significant contribution in the prediction of these adverse pregnancy outcomes. Crude and adjusted odds ratios (ORs) were derived for each pregnancy outcome.

Results: Seventy five thousand and four hundred women were included in the study, of whom 57,564 were Caucasian and 11,395 African. Compared to Caucasian ethnic origin, African women were more likely to develop PE [OR (95% CI): 2.77 (2.49-3.09), p<0.0001], GH [OR 1.38 (1.23-1.56), p<0.0001], SGA [OR 3.48 (3.16-3.83), p<0.0001], stillbirth [OR 2.42 (1.87-3.12), p<0.0001], GDM [OR 1.82 (1.59-2.07), p<0.0001], PTD prior to 37 weeks gestation [OR 1.33 (1.23-1.44), p<0.0001], and emergency CS [OR 2.42 (1.87-3.12), p<0.0001]. On the other hand, African women were less likely to develop LGA and OC [OR (95% CI): 0.63 (0.58-0.67) and 0.47 (0.32-0.69) respectively; p<0.0001 for both].

Conclusion: Compared to Caucasian ethnic background, women of African origin have a different risk profile for adverse pregnancy outcomes. This difference should be taken into account when calculating an individualised adjusted risk or when tailoring antenatal care.