McNeilly A S, Glasier A F, Howie P W, Houston M J, Cook A, Boyle H
Clin Endocrinol (Oxf). 1983 Aug;19(2):167-73. doi: 10.1111/j.1365-2265.1983.tb02978.x.
During studies on the resumption of fertility postpartum in 12 breast feeding mothers who were using no contraception, eight pregnancies occurred. In seven cases these pregnancies occurred while the mothers continued to breast feed while in one it occurred within 2 weeks of weaning. In two cases pregnancy occurred prior to first postpartum menstruation but followed an abrupt decline in suckling frequency and duration resulting in resumption of follicular development and ovulation. In the remaining six cases, pregnancy was preceded by between 1 and 7 menstrual cycles, the majority of which (13/19) had deficient luteal phases or were anovular (4/19). In all mothers a significant decrease in the suckling frequency and duration observed during lactational amenorrhoea had occurred prior to the resumption of ovulation and conception. No mother conceived with a suckling frequency of greater than three times per day although some mothers ovulated without conceiving when suckling four times per day. The results suggests that if a breast feeding mother wishes to rely upon the infertility associated with lactational amenorrhoea, she must suckle at least five times per day with a total suckling duration of more than 65 min per day (more than 10 min per feed). Any reduction below either of these limits may result in a return of fertility.
在对12名未采取避孕措施的哺乳期母亲产后生育恢复情况的研究中，有8例怀孕。其中7例怀孕发生在母亲持续哺乳期间，1例发生在断奶后2周内。2例怀孕发生在产后首次月经之前，但在哺乳频率和持续时间突然下降后，导致卵泡发育和排卵恢复。在其余6例中，怀孕前有1至7个月经周期，其中大多数（13/19）黄体期不足或无排卵（4/19）。在所有母亲中，在排卵和受孕恢复之前，哺乳期闭经期间观察到的哺乳频率和持续时间均有显著下降。没有一位母亲在每天哺乳超过三次的情况下怀孕，尽管有些母亲在每天哺乳四次时排卵但未受孕。结果表明，如果哺乳期母亲希望依靠与哺乳期闭经相关的不孕，她必须每天至少哺乳五次，总哺乳时间超过每天65分钟（每次哺乳超过10分钟）。低于这些限度中的任何一个都可能导致生育能力恢复。
