Efficacy of the symptothermal method of natural family planning in lactating women after the return of menses

Am J Obstet Gynecol. 1991 Dec;165(6 Pt 2):2037-9. doi: 10.1016/s0002-9378(11)90575-4.


This study was designed to determine the efficacy of the symptothermal method of natural family planning during lactation. Although the method appears to give a reasonable reflection of fertility potential over time, it overlaps with the profound influence of lactation in both ovulation suppression and the delay of luteal phase adequacy. Further analysis is planned to attempt to identify those particular mucus signs and symptoms that are helpful during the transition from lactational amenorrhea to normal cycling.

PIP: The efficacy of the symptothermal method of natural family planning (NFP), in the 1st 3 cycles after cessation of postpartum lactational amenorrhea was assessed in 25 women. The women recorded basal body temperature, bleeding/spotting, and mucus symptoms. Their estrone glucuronide, LH and pregnanediol glucuronide were assayed in timed urine samples. They continued in the study on average 13 months (range 9-17 months). In the 1st cycle ovulation as determined by basal body temperature was 4 days behind ovulation defined as LH peak + 1 day. Over 3 subsequent cycles, timing of these end-points approached 1 day. Similarly, in the 1st cycle, the length of the luteal phase tended to be 10 days, especially if it occurred 6 months postpartum. 25% did so between 200-300 days postpartum, and 15% did so 400 days postpartum. These results are being analyzed in terms of breastfeeding behavior.

MeSH terms

  • Body Temperature*
  • Family Planning Services / methods*
  • Female
  • Humans
  • Lactation / physiology*
  • Luteinizing Hormone / urine
  • Menstrual Cycle / physiology
  • Menstrual Cycle / urine
  • Ovulation / physiology
  • Pilot Projects


  • Luteinizing Hormone