AN ASSOCIATION BETWEEN ELEVATED LEVELS OF HUMAN CHORIONIC-GONADOTROPIN IN THE MIDTRIMESTER AND ADVERSE PREGNANCY OUTCOME

OBJECTIVE: Unexplained elevations in maternal serum alpha-fetoprotein in the midtrimester are associated with adverse pregnancy outcome. Rec ently it has also been suggested that elevations of maternal serum hum an chorionic gonadotropin in the second trimester may be associated wi th adverse pregnancy outcome. STUDY DESIGN: We conducted a cohort stud y of 460 women at Swedish Medical Center, Seattle, Washington, between Jan. 1, 1990, and Aug. 15, 1991, inclusive. Entry criteria for the co hort included (1) triple screen analysis (maternal serum alpha-fetopro tein, human chorionic gonadotropin, unconjugated estriol) between 15 a nd 18 weeks' gestation, (2) a risk for Down syndrome of more than one in 195 on the basis of triple screen analysis, (3) study group human c horionic gonadotropin greater-than-or-equal-to 2 multiples of the medi an and referent group less-than-or-equal-to 2 multiples of the median, alpha-fetoprotein less-than-or-equal-to 2 multiples of the median, un conjugated estriol greater-than-or-equal-to 0.5 multiples of the media n, and (4) chromosomally normal single gestation without anomalies. Cu mulative incidence risk ratios were estimated for each pregnancy outco me as a measure of the relative association with elevated human chorio nic gonadotropin (greater-than-or-equal-to 2.0 multiples of the median ) and adverse pregnancy outcome: low birth weight, less-than-or-equal- to 2500 gm; preterm delivery, <37 weeks' gestation; and small for gest ational age, less-than-or-equal-to 10th percentile. The Mantel extensi on test was used to evaluate any apparent linear trend in risk between level of human chorionic gonadotropin and adverse pregnancy outcome. RESULTS: Elevated human chorionic gonadotropin levels were associated with an increased risk for low birth weight (relative risk = 4.0), pre term delivery (relative risk = 2.8), and small for gestational age (re lative risk = 1.8). The risk for each adverse outcome increased with i ncreasing levels of human chorionic gonadotropin. CONCLUSIONS: Elevati ons of human chorionic gonadotropin in the midtrimester appear to be a ssociated with adverse pregnancy outcome. The magnitude of the risk co rrelates with the level of human chorionic gonadotropin. This risk app ears to be independent of the risk for adverse pregnancy outcome assoc iated with unexplained elevations of maternal serum alpha-fetoprotein.