A prospective multicentre study of the ovulation method of natural family planning. IV. The outcome of pregnancy. World Health Organization.

In a prospective, five-country study of the ovulation method of natural family planning, 175 pregnancies occurred, with known outcome in 163. There were 140 live births (86% of known outcome); 2 congenital malformations (1.2%), including 1 stillbirth; 16 spontaneous abortions (9.8%); and 6 induced abortions (3.7%). The rates of congenital malformations, stillbirths, and spontaneous abortions do not differ from outcomes in the community or outcomes associated with other fertility-regulating methods. Among the live births, there were 81 males and 59 females, a male proportion of 0.58. There were no significant differences in sex ratio from varying intervals between the likely act leading to conception and the estimated day of ovulation.