How critical is the timing of Rubella infection in pregnancy for risk of miscarriage or stillbirth?

The timing of a Rubella infection in pregnancy is particularly critical before 16 weeks gestation, as this is when the risk of miscarriage, stillbirth, and severe congenital anomalies is highest. During the early stages of pregnancy, the development of the fetus is particularly susceptible to teratogens like the Rubella virus. If a pregnant individual contracts Rubella during this window, the virus can significantly disrupt fetal development, leading to complications that include miscarriage or stillbirth.

Research shows that the first trimester, especially the first 12 to 16 weeks, is a crucial period for fetal organogenesis; the risk of adverse outcomes decreases as the pregnancy progresses. After 20 weeks and at term, the risks associated with Rubella infection are significantly reduced, as the major developmental processes have already occurred. Thus, the correct choice emphasizes the vulnerability of the fetus to Rubella infection during the early weeks of pregnancy.