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Racial variation in the association between gestational age and perinatal mortality: prospective study

BMJ 2007; 334 doi: https://doi.org/10.1136/bmj.39132.482025.80 (Published 19 April 2007) Cite this as: BMJ 2007;334:833
  1. Imelda Balchin, clinical research fellow1,
  2. John C Whittaker, professor2,
  3. Roshni R Patel, clinical academic training fellow3,
  4. Ronald F Lamont, consultant and reader4,
  5. Philip J Steer, professor1
  1. 1Academic Department of Obstetrics and Gynaecology, Imperial College Faculty of Medicine, Chelsea and Westminster Hospital, London SW10 9NH
  2. 2Department of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London WC1E 7HT
  3. 3Division of Obstetrics and Gynaecology, University of Bristol, St Michael's Hospital, Bristol BS2 8EG
  4. 4Department of Obstetrics and Gynaecology, Imperial College Faculty of Medicine, Northwick Park Hospital, Middlesex HA1 3UJ
  1. Correspondence to: I Balchin, 41 Hockley Avenue, East Ham, London E6 3AN balchin{at}doctors.org.uk
  • Accepted 23 January 2007

Abstract

Objectives To determine if the risks of perinatal mortality and antepartum stillbirth associated with post term birth increase earlier during pregnancy in South Asian and black women than in white women, and to investigate differences in the factors associated with antepartum stillbirth between the racial groups.

Design Prospective study using logistic regression analysis.

Setting 15 maternity units in northwest London from 1988 to 2000.

Participants 197 061 nulliparous women self reported as white, South Asian, or black, who delivered a single baby weighing at least 500 g at 24-43 completed weeks' gestation.

Main outcome measures Gestation specific perinatal mortality, antepartum stillbirth rates, and independent factors for antepartum stillbirth by racial groups.

Results The crude gestation specific perinatal mortality patterns for the three racial groups differed (P<0.001). The perinatal mortality rate among black women was lower than among white women before 32 weeks but was higher thereafter. Perinatal mortality was highest among South Asian women at all gestational ages and increased the fastest at term. After adjusting for the confounders of antepartum stillbirth (placental abruption, congenital abnormality, low birth weight, birth weight <10th centile, meconium passage, fever, maternal body mass index ≥30, and maternal age ≥30), the excess mortality among black women after 32 weeks was not significant. After adjusting for confounding, South Asian women still had a significantly higher risk of antepartum stillbirth (odds ratio 1.8, 95% confidence interval 1.2 to 2.7).

Conclusions The risk of perinatal mortality increased earlier in gestation among South Asian women than among white women. The most important factor associated with antepartum stillbirth among white women was placental abruption, but among South Asian and black women it was birth weight below 2000 g.

Footnotes

  • We thank the midwives, medical staff, and secretarial staff of the North West Thames obstetric units who collected and entered data into the North West Thames maternity database.

  • Contributors: IB wrote the first draft of the paper and helped refine the hypothesis, design the methodology, and analyse the data. JCW devised and supervised the statistical analysis. RP helped refine the hypothesis and carried out the initial analysis. RFL suggested variables for study. PJS formulated the original hypothesis and helped analyse the data and write the first draft. All authors helped edit the final draft and approved its contents. IB is guarantor.

  • Funding: None.

  • Competing interests: None declared.

  • Ethical approval: St Mary's local research ethics committee, London.

  • Accepted 23 January 2007
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