The Current Status of Postpartum Menstrual Resumption Delay and Associated Risk Factors in Japanese Women: An Adjunct Study of the Japan Environment and Children's Study.

Background: Prolonged postpartum amenorrhea is a sign of secondary infertility. However, there are no reports on postpartum menstrual resumption delay in Japanese women. We conducted an Adjunct Study of the Japan Environment and Children's Study (JECS) to elucidate the actual state of postpartum menstrual resumption delay in Japan and related factors.

Infant Suffocation Incidents Related to Co-Sleeping or Breastfeeding in the Side-Lying Position in Japan.

Co-sleeping and breastfeeding in the side-lying position have recently been pointed out as risk factors for suffocation in sleeping infants; however, there is no actual report on an "incident." "Incident" is defined as a tense or sobering experience without a consequential fatal suffocation accident. It is important to understand infant suffocation incidents to prevent accidents during co-sleeping and breastfeeding in the side-lying position.