Human Reproduction, Vol. 15, No. 1, 210-217,
January 2000
© 2000 European Society of Human Reproduction and Embryology
Birth weight in pre-eclamptic and normotensive twin pregnancies: an analysis of discordance and growth restriction
Department of Obstetrics and Gynaecology, Catholic University, School of Medicine, 00168 Rome, Italy
The aim of this study was to verify whether twin pregnancies complicated by pre-eclampsia were associated with a higher rate of inter-twin weight discordance or an increased prevalence of small for gestational age (SGA) neonates than in normotensive twin pregnancies. A 17 year retrospective study was undertaken by examining 76 twin pregnancies complicated by pre-eclampsia and comparing them with 400 normotensive twin pregnancies. The case notes were reviewed in reference to birth weight differences, birth order, pregnancy outcome and inter-twin birth weight discordance. Statistical analyses were performed with t-test, contingency tables, regression curves, rank sum test and non-parametric survival plots. Power analysis was also carried out. Pre-eclamptic twin pregnancies were delivered at similar weeks of gestation to normotensive. They resulted in a smaller size for the second twin the earlier the delivery week, while in normotensive twin pregnancies no significant difference occurred at any week. Twin pregnancies complicated by pre-eclampsia showed higher rates of SGA neonates among second twins than those with normal pressure. The >25% discordance was associated with lower gestational age at delivery in each group [mean (range) 33 weeks (27–38) versus 37 (29–41), P < 0.005 pre-eclampsia and 35 weeks (25–41) versus 38 (25–42), P < 0.001 normotensive]. In pre-eclampsia the concomitant occurrence of SGA second twin and the discordance >25% was associated with shorter gestation while the presence of SGA second twin alone was not.
Key words: birth weight discordance/growth restriction/pre-eclampsia/twin pregnancy