Final answer:
The menstrual cycle typically returns within 6 weeks to 6 months post-delivery, with the normal levels of estrogen being restored, leading to subsequent ovulatory cycles.
Step-by-step explanation:
The return of the menstrual cycle following delivery varies depending on several factors including breastfeeding status and individual hormonal changes. The nurse is correct in stating that the menstrual cycle can return and be anovulatory at first, with the normal levels of estrogen gradually being re-established. It generally takes about 6 weeks to 6 months for most women's estrogen levels to return to normal such that they are experiencing ovulatory cycles, although this can vary widely between individuals.