PP029. Gestational hypertension and birth weight in twin pregnancies

It is well known that hypertensive disorders of pregnancy are most frequent in twin pregnancies than in singleton ones. As demonstrated by a previous work of our group, twin pregnancies complicated by preeclampsia are associated with a higher rate of "small for gestational age" (SGA) neonates and inter-twin weight discordance than normotensive ones.

The present study investigates the effect of gestational hypertension (GH) on neonatal birth weight, inter-twin weight discordance and growth restriction rate among twin pregnancies.

A 26 year retrospective study was undertaken by examining 196 twin pregnancies complicated by GH, from January 1, 1980 to December 31, 2006, and comparing them to 912 normotensive twin pregnancies.

No significant differences were observed between the two groups in relationship to birth weight, inter-twin weight discordance and growth restriction rate, with a trend towards a higher birth weight in GH group. In normotensive group, the discordance >25% was associated with a lower gestational age at the delivery (p<0.00001). Moreover, the rate of pregnancies with SGA second twin gradually rose while paralleling the degree of discordance.

Contrary to preeclampsia in twin pregnancies the outcome of those complicated by GH is similar to normotensive ones. The trend towards a higher birth weight in GH seems apparently paradoxical, but it may reflect the role of uncomplicated hypertension in twin pregnancies: the increased blood pressure could be a physiologic response for more blood nutrient supply to the fetuses.