A study compared postpartum conception, menstruation and ovulation o f 299 Alaskan Eskimo female noncontraceptive users of which 242 nursed t heir infants and 57 did not with a control group of 115 women who were newly married or who had discontinued contraceptive use. 2 factors were found to differentiate nursing from nonnursing women in relation to postpartum conception as follows: the annovulatory period of postpartum amenorrhea is longer for nursing than for nonnursing women and the number of annovulatory cycles after menstruation recurs is greater for the former than for the latter. A comparison of pregnancy probability r ates for controls with those nursing and nonnursing women showed that the control had a significantly higher probability rate of pregnancy than did those in the adjusted groups for the first 6 months with the nursers and for months 2 through 6 for the nonnursers. Conception rates were under 10% in women breast-feeding for at least 9 months whereas about 75% of the nonnursing women were pregnant within a similar period of time. Life-table analyses of pregnancy probability rates indicated that on the average the anovulatory period post amenorrhea was 3 months for nonnursing and 4 months for nursing women. The consistency of these findings with those reported for Indian women suggest that the physiologic effect of nursing on conception rates is independent of climate.
Notes
From: Fortuine, Robert et al. 1993. The Health of the Inuit of North America: A Bibliography from the Earliest Times through 1990. University of Alaska Anchorage. Citation number 1109.