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Abstract
The contraceptive efficacy of breastfeeding was assessed in 236 healthy urban women
who were followed at monthly intervals during the first postpartum year. Proportional
hazard models were used to evaluate the influence of time postpartum, menstrual status
and breastfeeding pattern upon the risk of pregnancy.
Time and menstrual status had a highly significant effect on this risk. Those women
who remained in amenorrhea had cumulative probabilities of pregnancy of 0.9% and 17%
at 6 and 12 months postpartum, respectively. In those who recovered menstrual cycles,
the risk rose to 36% and 55% at 6 and 12 months, respectively. Milk supplementation
also increased significantly the risk when considered alone but not when time and/or
menstrual status were included in the analysis. However, amenorrheic women who introduced
bottle feeding, had a higher risk of pregnancy after 6 months postpartum than those
who remained fully nursing. The analysis was unable to detect a significant influence
of the nursing frequency.
The results confirm that lactational amenorrhea is an effective contraceptive during
the first six months postpartum. The first postpartum bleeding marks a great increase
in the risk of pregnancy. Supplementation also increases the risk, particularly in
amenorrheic women.
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Article info
Publication history
Accepted:
February 6,
1991
Received:
November 20,
1990
Identification
Copyright
© 1991 Published by Elsevier Inc.
