MATERNAL SERUM MARKERS LEVELS IN CONSECUTIVE PREGNANCIES - A POSSIBLEGENETIC PREDISPOSITION TO ABNORMAL LEVELS

The study comprised 2,361 with two consecutive normal uncomplicated pr egnancies screened at 15-20 weeks gestation for maternal serum alpha-f etoprotein levels (AFP). In 1,816 of these women, maternal serum human chorionic gonadotropin (hCG) levels were tested as well. The proporti on of women who had a second high AFP level (greater than or equal to 2.0 MOM) in their subsequent pregnancy was 6.5-fold higher as compared with the proportion of women who had normal levels of AFP in their fi rst tested pregnancy, The relative chance of having a second positive result of a low level of AFP (AFP less than or equal to 0.5 MOM) in su bsequent pregnancies was 3.8-fold higher The relative chances of havin g a second positive result of high or low levels of hCG were 3.9- and 2.2-fold higher, respectively. It is concluded that there is a predisp osition for abnormal levels of serum markers that is influenced by gen etic and/or environmental factors, Therefore it is suggested that the individual's risk of having a Down syndrome baby, or other adverse pre gnancy outcome that is derived from the serum markers' levels, should be adjusted taking into account unexplained high or low levels in prev ious pregnancies, A screening policy is suggested which is designed to yield a lower false-positive rate without affecting the detection rat e of abnormal pregnancies. More data are needed before an accurate adj ustment based on previous results can be made. (C) 1996 Wiley-Liss, In c.