What is the main reason why a woman who is older than 35 years may have difficulty achieving pregnancy?

Choice A reason: Variability refers to the fluctuations in the FHR that are irregular in amplitude and frequency. It reflects the balance between the sympathetic and parasympathetic nervous systems of the fetus. A normal variability is between 6 and 10 beats/min, which indicates a healthy and well-oxygenated fetus.

Choice B reason: Late decelerations are decreases in the FHR that begin after the peak of a contraction and return to the baseline after the contraction ends. They are caused by uteroplacental insufficiency, which means that the placenta is not delivering enough oxygen and nutrients to the fetus. Mild late decelerations are not reassuring and may indicate fetal hypoxia or acidosis².

Choice C reason: FHR should change as a result of fetal activity, such as movement, sleep, or stimulation. A change in the FHR indicates a responsive and well-oxygenated fetus. A lack of change in the FHR may indicate fetal distress or compromise.

Choice D reason: The average baseline rate is the mean FHR rounded to increments of 5 beats/min during a 10-minute window, excluding periods of marked variability, accelerations, or decelerations. A normal baseline rate is between 110 and 160 beats/min. A baseline rate between 100 and 140 beats/min is not necessarily abnormal, but it may indicate fetal bradycardia (slow heart rate) or tachycardia (fast heart rate), depending on the gestational age and other factors.

Choice A: February 6-7 is incorrect. This is too late for the woman's fertile period, which occurs around the time of ovulation. Ovulation usually happens about 14 days before the next period starts, which would be around January 22 for a 28-day cycle¹.

Choice B:In a 28-day menstrual cycle, ovulation typically occurs around day 14 (counting from the first day of the last menstrual period). Since the first day of the last period is January 8, day 14 falls on January 22. The fertile window consists of the five days leading up to ovulation and the day of ovulation (January 17–22), as sperm can survive in the reproductive tract for up to 5 days, and the egg remains viable for about 24 hours after ovulation.January 22-23 is the most fertile period, with ovulation occurring around January 22 and the egg remaining viable for fertilization on January 23.

Choice C: January 30-31 is incorrect. This is after the woman's fertile period, which ends about a day after ovulation. Ovulation usually happens about 14 days before the next period starts, which would be around January 22 for a 28-day cycle.

Choice D: January 14-15 corresponds to cycle days 7-8, which is too early for ovulation in a typical 28-day cycle. Ovulation generally occurs around day 14 (January 22). The follicular phase (the first half of the cycle) is when the follicles in the ovary mature, and estrogen levels rise to trigger ovulation. At this point (January 14-15), the egg is not yet released, and the uterus is still preparing for ovulation, making conception unlikely.