The contraceptive effects of lactation. Failure to appreciate these effects resulted in unnecessary stress for a couple.

Lactational infertility is being investigated in mothers who delivered in the Simpson Memorial Maternity Pavilion in Edinburgh, Scotland. A group of breast feeding and a group of bottle feeding mothers were monitored. Weekly urinary total estrogen, pregnanediol excretion, and fortnightly plasma gonadotropins and prolactin concentrations were measured to determine the relationship between the resumption of menstruation and 1st postpartum ovulation. A research sister visited each mother at home every 2 weeks to collect a 10 ml sample of venous blood and to check on the progress of breast feeding. Although lactation is not a totally reliable contraceptive method, a mother is very unlikely to ovulate when she is fully breast feeding in the early weeks after delivery and particularly if she is giving night-time feeds. When the timing of 1st ovulation was compared in 7 bottle feeding mothers and 10 breast feeding mothers, ovulation was delayed in all lacting women and returned only when the mother started to wean her baby. A case history is reported of 1 patient who highlights the need for a deeper understanding of this natural contraceptive mechanism. The patient was Roman Catholic, mother of 4 children, and she and her husband wanted to practice only natural methods of contraception. She was informed that her weekly urinary steroid levels showed no evidence of ovulation, but she remained unconvinced and requested information and guidance on cervical mucus assessment. By choosing to stop breast feeding to return to a familiar contraceptive method, the patient increased the risk of unwanted conception. A prolonged period of lactation may be an effective method for couples who want to space their children, and this option should be explained to couples.