Preliminary evidence for associations between second-trimester human chorionic gonadotropin and unconjugated oestriol levels with pregnancy outcome in Down syndrome pregnancies

Abstract

Fifty-six cases of Down syndrome were identified in a population of women who had undergone maternal serum triple marker screening [alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG), and unconjugated oestriol (uE3) analyses]. These affected pregnancies represented all known cases present in the population of 34,368 women screened. Using a 1:270 mid-trimester Down syndrome risk to define the screen-positive group, 42 affected pregnancies were screen-positive (medians: AFP = 0.79 MOM, hCG = 2.13 MOM, uE3 = 0.62 MOM, age 34.6 years) and 14 pregnancies were screen-negative (medians: AFP = 0.82 MOM, hCG = 1.57 MOM, uE3 = 0.92 MOM, age 24.2 years). Four affected pregnancies were associated with in utero death and each of these cases was associated with relatively extreme values of AFP, hCG, and uE3, including the three highest levels of hCG in the entire series of Down syndrome pregnancies. Twenty-nine (15 screen-positive and 14 screen-negative) affected pregnancies resulted in liveborns. Down syndrome pregnancies had a significantly shorter gestational term than controls, and Down syndrome babies were also lighter than controls, even after adjustment for sex and gestational age. In affected pregnancies, a low uE3 level appeared to be associated with a greater chance of a small-for-gestational age baby. No correlations could be demonstrated between AFP or hCG levels and gestational age-adjusted term weight. Based on this small series, it would appear that uE3 may be particularly useful in detecting those Down syndrome cases associated with small-for-gestational age fetuses. A very high hCG value may indicate a higher probability of fetal death.