[Effect of a combined oral contraceptive on lactation and growth of the infant]

Rev Chil Obstet Ginecol. 1983;48(5):372-80.
[Article in Spanish]


PIP: This work describes a study conducted in a University of Chile hospital to determine the influence of a combined oral contraceptive (OC) containing 30 mcg of ethinyl estradiol and 150 mcg of norgestrel on lactation and infant growth. 103 women exclusively breastfeeding began using the OC on day 30-35 postpartum, 59 women exclusively breastfeeding whose infants gained at least 20 gm daily during the 3rd month of life began using the OC on day 90 postpartum, and 109 women exclusively breastfeeding received an injectable placebo on day 30 postpartum and an IUD or spermicides on day 90 if desired. A subgroup of 82 women from the 30-day control group who continued breastfeeding exclusively at day 90 postpartum and whose infants gained at least 20 gm daily during the 3rd month were a control group for the women beginning OCs on day 90. Follow-up visits were arranged every 10 days through the 3rd month and every 30 days subsequently through 1 year. At the beginning of the study, treatment and control groups were similar in age, parity, weight, maternal hemoglobin, and sex and weight of infants. 63 women were excluded from the study while still breastfeeding for a variety of reasons including loss to follow-up. The main reason for exclusion of OC users was termination of OC use or change of method. 11 pregnancies occurred in controls using spermicides or no contraception. Among women using OCs starting at day 30 postpartum, the percentage exclusively breastfeeding was significantly lower than among controls beginning in the 4th month, and a higher percentage of cases gave supplementary feedings on the advice of their physicians or their own decision. At 6 months, 61% of controls and 40% beginning OC use at 30 days were still breastfeeding exclusively. Fewer women beginning OC use at 90 days than controls were exclusively breastfeeding at 6 months, and a higher proportion were giving supplementary feedings on medical advice. The 2 treatment groups had smaller weight gains than their control groups in the 1st month of treatment. Total weight gain to the 6th month was significantly different for babies whose mothers began OC use at 30 days but not for those beginning use at 90 days. The average absolute weight of infants in the groups beginning treatment at 30 days was significantly lower at several ages but the differences were small. Growth of infants was good in most cases. Only 6 presented significant intercurrent illnesses. There were no deaths. No pregnancies occurred in women using OCs and tolerance was good. 1 woman discontinued use for metrorrhagia. It was concluded that the OC tested moderately inhibits lactation, especially when use is begun at the beginning of the 2nd postpartum month.

Publication types

  • English Abstract

MeSH terms

  • Adolescent
  • Adult
  • Body Weight / drug effects
  • Contraceptives, Oral / pharmacology*
  • Contraceptives, Oral, Combined / pharmacology*
  • Ethinyl Estradiol / pharmacology*
  • Female
  • Growth / drug effects*
  • Humans
  • Infant, Newborn
  • Lactation / drug effects*
  • Male
  • Norgestrel / pharmacology*
  • Postpartum Period
  • Pregnancy


  • Contraceptives, Oral
  • Contraceptives, Oral, Combined
  • Norgestrel
  • Ethinyl Estradiol