The timeline for a woman's fertility after giving birth varies significantly based on breastfeeding status. For women who are not breastfeeding, menstrual cycles typically resume within about nine months postpartum, often coinciding with the weaning process. In contrast, breastfeeding can delay the return of menstrual cycles, leading to a longer gap before fertility returns. It's important to note that breastfeeding is not a reliable method of birth control, and some women may find themselves pregnant sooner than expected, while others may take longer to resume their cycles. Instances of siblings being born within 20 months of each other are common, highlighting the variability in fertility post-birth.