Birth weight in pre-eclamptic and normotensive twin pregnancies: an analysis of discordance and growth restriction

Abstract

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.

Is gestational hypertension beneficial in twin pregnancies?

“…In addition, the present study shows that the inter-twin discordance was the consequence of the trend to growth restriction of the second twin (twin B) in both hypertensive and normotensive pregnancies, confirming the data observed in our previous work [8]. Both in hypertensive and normotensive twin pregnancies, the rate of pregnancies with SGA twin B rose as the degree of discordance increased, while the rate of pregnancies with both adequate-for-gestational age (AGA) twins declined as the degree of discordance increased.…”

“…Similar to the our previous study about preeclamptic twin pregnancies [8], the present study demonstrates that there was a relationship between gestational age at delivery and percentage weight discordance both in the gestational hypertensive and in the normotensive group.…”

“…In our previous report [8], a comparison of twin pregnancies complicated by preeclampsia versus normotensive ones, showed that preeclampsia was observed associated with a higher rate of SGA neonates than that observed in the normotensive pregnancies. On the contrary, in the present report the infants from twin pregnancies complicated by gestational hypertension seemed to have a higher birthweight trend than that observed in infants born to normotensive women.…”

“…On this topic, our previous work [8] suggested that the discordance >25% was associated with shorter gestational duration both in preeclamptic and in normotensive women. Probably, inter-twin discordance was clinically determinant in the decision of timing of delivery because of the associated conditions: oligo-anhydramnios, foetal distress and abnormal Doppler velocimetry.…”

“…Recent data report that the incidence of gestational hypertension and preeclampsia is double (12.9% vs. 6.3%) and three times greater (12.7% vs. 4.9%) respectively, in twin pregnancies compared to singleton ones [7]. Furthermore, singleton and twin pregnancies complicated by preeclampsia are more frequently characterized by low birth weight and small for gestational age (SGA) neonates compared to normotensive pregnancies [2,8,9]. So far, few studies analyzed the effect of gestational hypertension not complicated by preeclampsia on neonatal outcomes among twin pregnancies.…”