Association between second-trimester isolated high maternal serum maternal serum human chorionic gonadotropin levels and obstetric complications in singleton and twin pregnancies

OBJECTIVE: The purpose of this study was to examine the clinical significance of high maternal serum human chorionic gonadotropin levels in the second trimester in singleton and twin pregnancies within the Ontario maternal serum screening program STUDY DESIGN: The study group comprised 564 women with singleton pregnancies with total maternal serum human chorionic gonadotropin levels of greater than or equal to 4.0 multiples of the median (MoM) and serum marker alpha-fetoprotein levels of <2.0 MoM. The cases were matched with 1692 control subjects who had both serum marker alpha-fetoprotein levels and maternal serum human chorionic gonadotropin levels of <2.0 MoM. The second part of the study comprised 93 twin pregnancies with maternal serum human chorionic gonadotropin levels of greater than or equal to5.0 MoM and serum marker alpha-fetoprotein levels of <4.0 MoM; the control group (n = 1496) had serum marker alpha-fetoprotein levels of <4.0 MoM and maternal serum human chorionic gonadotropin levels of <5.0 MoM. The final part of the study included 25 women with extremely high maternal serum human chorionic gonadotropin levels (greater than or equal to 10 MoM). RESULTS: Of the singleton pregnancies with maternal serum human chorionic gonadotropin levels of greater than or equal to 4.0 MoM, 22.5% had severe adverse obstetric outcomes, compared with only 10.9% of the matched control population (P = .001). Women with markedly elevated maternal serum human chorionic gonadotropin levels had significantly increased risks of having spontaneous miscarriage, small-for-gestational-age infants, pregnancy-associated hypertensive disorder, and preterm delivery. Of the women with twin pregnancies with high maternal serum human chorionic gonadotropin levels (greater than or equal to 5.0 MoM), 71% had at least one complication (such as miscarriage and preterm delivery) compared with 55.3% in the control group. Finally, 23 of 25 women with extremely high maternal serum human chorionic gonadotropin levels (greater than or equal to 10 MoM) had serious adverse outcomes (such as fetal abnormalities, pregnancy-associated hypertensive disorder, premature separation of placenta, intrauterine growth restriction, neonatal respiratory distress syndrome, and neonatal jaundice). CONCLUSION: Pregnancies with an elevated maternal serum human chorionic gonadotropin level are associated with adverse obstetric outcomes. Increased maternal and fetal surveillance is warranted in these pregnancies.