This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General obstetrics, Subject name: Gynaecology & Obstetrics
Without breastfeeding the first menstrual flow usually begins --- weeks after delivery? 
Select and explain. 
A. 2-4 weeks, B. 4-6 weeks, C. 6-8 weeks, D. 8-10 weeks
C: 6-8 weeks
Answer: C: 6-8 weeks 
Explanation: This is variable and depends upon whether the woman is lactating. Nonlactating mothers have an early resumption of menses by about 6-8 weeks. In nursing mothers, approximately 70% are amenorrheic until 4-6 months (refer pgno:424 Sheila 2 nd edition)