regular menstruation during early pregnancy

例句：

1. 1. During early pregnancy, regular menstruation is a normal part of the cycle.
   在早期怀孕期间，规律的月经是周期的正常部分。
2. 2. Women often experience irregular menstruation during their childbearing years.
   女性在生育年龄经常经历不规律的月经。
3. 3. The doctor advised her to monitor her menstrual cycles and adjust her medication accordingly.
   医生建议她监测月经周期并相应调整药物。