Placental maturity, hypertensive disorders of pregnancy and birth weight

To compare maturity of placentas from women with hypertensive disorders with those from normotensive pregnancies and to determine the relationship between placental maturity (PM) and the diagnosis of small-for-gestational-age (SGA) in the newborns.

We examined placental stained specimens from women with normotensive pregnancies (n = 100), diagnosis of gestational hypertension (n = 38), mild (n = 10), or severe preeclampsia (n = 34) in an optical microscope. Placental Maturity Index (PMI) was calculated as the number of vasculo-syncytial membranes (VSM) in 1 mm(2) divided by VSM thickness (µm). Hypermaturity was defined as >90th percentile of the PMI from placentas of normotensive pregnancies. Newborns were classified as SGA, adequate-for-gestational-age (AGA) or large-for-gestational-age (<10th, 10-90th, and >90th percentile from weight for gestational age reference tables, respectively).

PMI in preeclamptic women (taking together mild and severe preeclampsia, PMI = 43.4 ± 1.6) was significantly higher than in normotensive women (PMI = 36 ± 2, p = 0.045). Hypermaturity was more frequent (p < 0.05) in placentas from women with preeclampsia than in those from normotensive women only in preterm pregnancies (<37 weeks), but not in those at term (p = 0.41). The frequency of hypermaturity in placentas from women with gestational hypertension was not statistically different than in normotensive women. Hypermaturity was also more frequent in placentas from SGA (OR = 2.63, p < 0.05) than in AGA newborns.

The PMI was increased in preeclampsia, but not in gestational hypertension. Placental hypermaturity was also associated with the diagnosis of SGA in newborns. PM might have a role in the relationship between maternal factors and SGA.