A Life Table of Pregnancy Terminations and Correlates of Fetal Loss

Partial findings in cohort study of the relationship between maternal morbidity and pregnancy outcome based on the medical records of 32 medical group of the Health Insurance Plan (HIP) of Greater New York are discussed. The conditions for which women receive medical care prior to conception and during pregnancy are related to the occurrence of fetal mortality prematurity congenital anomalies and other morbid conditions that appear in the first 2 years after birth. Measures fetal loss at various stages of pregnancy is measured and the relationship of the mothers age gravidity and prior pregnancy experiences to fetal mortality with particular emphasis on early pregnancy loss is reexamined. This phase of the research has been completed for a segment of the 2-year cohort under study. Included in the study reported here are the pregnancy terminations among women whose last menstrual period (LMP) prior to pregnancy began between March 1 1958 and February 28 1989 and who received care from HIP obstetricians. This totals 6844 pregnancies. The final results will include these women and a 2nd years cohort of women with L7Ps from March 1 1959 through February 29 1960. The 2-year experience will involve about 15000 pregnancies. Data were obtained from routine reports of medical care rendered HIP members physicians and the medical charts of the obstetricians. The probability of a pregnancy ending in a particular week of gestation as determined from physicians records follows a bimodal distribution. The initial peak occurs during the previability period psecifically at 10 weeks gestation as measured from the LMP. The 2nd and much higher peak occurs at 40 weeks which is generally regarded as approximating the desired full-term period of gestation. The rate of total fetal loss is 142/1000 pregnancies. 48% of the loss is under 12 weeks gestation; another 32% is at 12-19 weeks; and 12% is at 20 weeks or more gestation. Fetal loss increases with age of mother after age 20. This relationship is found at all durations of pregnancy. Total fetal loss also varies directly with gravida of the mother. In those with terminations at 20 weeks or more gestation gravida 1 women have a higher range of fetal loss than gravida women. At the early gestation ages 12 weeks or less the situation is reversed with gravida 1 women having the lower rate. Outcome of the last prior pregnancy is a major factor in the outcome of the current pregnancy. Women whose last pregnancy ended in a fetal death have twice have twice as high a loss rate in their next pregnancy as other women.