Objective: To evaluate the influence of maternal age on pregnancy loss rates after early documentation of fetal cardiac activity by transvaginal ultrasound (US) in previously infertile women.
Design: Retrospective, observational study.
Setting: Tertiary fertility center.
Patients: One hundred eighty-six previously infertile women 20 to 43 years of age undergoing ovulation induction.
Main outcome measure: We analyzed 201 clinical pregnancies in which cardiac activity had been documented by transvaginal US 35 to 42 days after ovulation in a previously infertile population treated at a tertiary fertility center. Patient age, infertility diagnosis, ovulation induction protocol, and mode of insemination were analyzed by chi 2, Fisher's exact test and logistic regression analyses.
Results: A profound increase in spontaneous abortion rates occurred as a function of maternal age in this population (chi 2 for trend = 15.1). A spontaneous abortion rate of 2.1% was observed for maternal ages < or = 35 years but this rate increased to 16.1% for patients > or = 36 years (odds ratio, 8.72; 95 percent confidence interval 2.3 to 32.9). A fivefold increase in spontaneous abortion rate was observed in women > or = 40 years compared with women 31 to 35 years (3.8% versus 20.0%. Infertility diagnosis, mode of insemination, and ovulation induction protocol were not associated with an increased risk of spontaneous abortion.
Conclusions: The incidence of pregnancy loss after confirmation of early fetal cardiac activity by transvaginal US is substantially greater in infertile patients than previously reported, when considered as a function of maternal age. In particular, patients > or = 36 years should be counseled that their risk of spontaneous abortion is significant even after fetal heart motion is present on transvaginal US. Cautious optimism and greater surveillance may be required during the first trimester of pregnancy in these women.