Birth order, gestational age, and risk of delivery related perinatal death in twins: retrospective cohort study

Smith, G.C., Pell, J.P. and Dobbie, R. (2002) Birth order, gestational age, and risk of delivery related perinatal death in twins: retrospective cohort study. British Medical Journal, 325(7371), pp. 1004-1006. (doi: 10.1136/bmj.325.7371.1004)



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Objective: To determine whether twins born second are at increased risk of perinatal death because of complications during labour and delivery. Design: Retrospective cohort study. Setting: Scotland, 1992 and 1997. Participants: All twin births at or after 24 weeks' gestation, excluding twin pairs in which either twin died before labour or delivery or died during or after labour and delivery because of congenital abnormality, non-immune hydrops, or twin to twin transfusion syndrome. Main outcome measure: Delivery related perinatal deaths (deaths during labour or the neonatal period). Results: Overall, delivery related perinatal deaths were recorded for 23 first twins only and 23 second twins only of 1438 twin pairs born before 36 weeks (preterm) by means other than planned caesarean section (P>0.99). No deaths of first twins and nine deaths of second twins (P=0.004) were recorded among the 2436 twin pairs born at or after 36 weeks (term). Discordance between first and second twins differed significantly in preterm and term births (P=0.007). Seven of nine deaths of second twins at term were due to anoxia during the birth (2.9 (95% confidence interval 1.2 to 5.9) per 1000); five of these deaths were associated with mechanical problems with the second delivery following vaginal delivery of the first twin. No deaths were recorded among 454 second twins delivered at term by planned caesarean section. Conclusions: Second twins born at term are at higher risk than first twins of death due to complications of delivery. Previous studies may not have shown an increased risk because of inadequate categorisation of deaths, lack of statistical power, inappropriate analyses, and pooling of data about preterm births and term births.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Pell, Professor Jill
Authors: Smith, G.C., Pell, J.P., and Dobbie, R.
Subjects:R Medicine > RA Public aspects of medicine
R Medicine > RG Gynecology and obstetrics
College/School:College of Medical Veterinary and Life Sciences > School of Health & Wellbeing > Public Health
College of Medical Veterinary and Life Sciences
Journal Name:British Medical Journal
Journal Abbr.:BMJ
ISSN (Online):1756-1833
Copyright Holders:Copyright © 2002 BMJ
First Published:First published in British Medical Journal 325(7371):1004-1006
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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