If a woman has a 36-day menstrual cycle and her last menstrual period started on January 8, when is her next fertile period?

To determine the next fertile period for a woman with a 36-day menstrual cycle, we must first understand the timing of ovulation. Ovulation typically occurs about 14 days before the start of the next menstrual period. In this case, if the last menstrual period began on January 8, the next expected menstrual period will occur 36 days later, which would be on February 13.

Calculating the ovulation date involves subtracting 14 days from February 13, resulting in an estimated ovulation date of February 1. The fertile period usually spans a few days before and after ovulation, typically considered to be around five days prior and one day post-ovulation. Therefore, the fertile window would be from January 28 to February 2.

In this context, the correct fertile period indicated in the choice provided aligns with January 30-31, as these dates fall within the range leading up to the ovulation date. This is why this choice represents the best answer regarding the timing of the fertile period for this particular menstrual cycle.

Identifying the accurate fertile period is crucial for couples trying to conceive, as it increases the likelihood of successful fertilization during the ovulation window.