Second trimester serum free beta human chorionic gonadotrophin levels as a predictor of pre-eclampsia.

BACKGROUND

To prospectively assess maternal serum free beta human chorionic gonadotrophin (beta hCG) estimation between 15 and 18 weeks gestation, as a screening test for pre-eclampsia in primigravid women.

METHODS

A prospective longitudinal study in a University Teaching Hospital. The study population was 430 primigravid women, who had maternal serum free beta hCG levels measured as part of antenatal serum screening for Down's Syndrome in the second trimester, who booked consecutively within the unit and went on to deliver on the unit's labor ward. These women were followed during their subsequent pregnancy and categorized into those who remained normotensive and those who developed pre-eclampsia on both clinical and biochemical grounds. The beta hCG levels were used to construct a receiver operator characteristics curve (ROC) to assess the screening potential for pre-eclampsia.

RESULTS

Nineteen (4.4%) women in the study group developed pre-eclampsia. The median second trimester free beta hCG multiples of the median (MOM) was significantly elevated compared to that of the control group (1.52 vs 1.10, p=0.03). The ROC curve shows that for a sensitivity of 79%, the specificity was only 54%.

CONCLUSIONS

Maternal serum free beta hCG alone measured in the second trimester is not clinically useful as a screening test for pre-eclampsia in primigravid women. It has, however, some predictive value.