Seasonality of induced abortion in North Carolina

J Biosoc Sci. 1998 Jul;30(3):321-32. doi: 10.1017/s0021932098003216.


This paper examines the seasonality of induced abortion in North Carolina between 1980 and 1993. Distinct seasonal patterns are found, with a peak in February and a valley in September. These patterns correspond to the implicit seasonality of conceptions associated with the seasonality of birth pattern. One notable difference from the general pattern is among unmarried women aged 18 and younger. They have the February peak and an additional peak in August that may be associated with the summer vacation from school.

PIP: This study examined patterns of seasonality in induced abortion in North Carolina. Data were obtained for 1980 and 1993 from the North Carolina State Center for Health Statistics and reported by providers. Monthly frequencies were adjusted by dividing the number of abortions per month by the expected monthly totals, which were yearly totals multiplied by the ratio of days in a month to days in a year. Analysis relied on plots of the average number of abortions in each month for total population and by age, marital status, and race. Seasonal stability was tested across the years. Dummy variable regressions were estimated for total population and targeted groups for specific months. Regression models testing for seasonality were tested for 3 groups of women. Findings indicate that there were more abortions in winter months, with a peak in February. Abortions declined through April, and stabilized during May through August, at a level that was the stable average for the year. During September through December, abortions were fairly stable and lower. Patterns were similar between married and unmarried women. Almost 70% of abortions occurred between 7-10 weeks gestation. Seasonal patterns for unmarried women aged under 18 years differed. For these women, abortions peaked in August. Tests for stable seasonality revealed lack of uniformity across months. Abortions were higher in August for total population, Blacks and Whites. The seasonal pattern of abortions matched in general the seasonal patterns of conceptions and births in North Carolina and births in the US.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Abortion, Induced / statistics & numerical data*
  • Adult
  • Female
  • Humans
  • North Carolina
  • Seasons*