A nurse is conducting an in-service program for a group of nurses working at the women's health facility about the causes of spontaneous abortion. The nurse determines that the teaching was successful when the group identifies which condition as the most common cause of first trimester abortions?

Choice A Reason: This is incorrect because cervical insufficiency is a condition where the cervix dilates prematurely and painlessly during pregnancy, leading to preterm delivery or second trimester abortion. It is not a common cause of first trimester abortion, which occurs before 12 weeks of gestation.

Choice B Reason: This is incorrect because uterine fibroids are benign tumors that grow in or on the uterus. They may cause heavy bleeding, pain, or infertility, but they are not a common cause of first trimester abortion. They may increase the risk of miscarriage in later stages of pregnancy.

Choice C Reason: This is correct because fetal genetic abnormalities are the most common cause of first trimester abortion, accounting for up to 70% of cases. Fetal genetic abnormalities are errors in the number or structure of chromosomes that occur during fertilization or cell division. They can cause developmental defects or fetal demise that result in spontaneous abortion.

Choice D Reason: This is incorrect because maternal disease is not a common cause of first trimester abortion. Maternal disease refers to any medical condition that affects the mother's health or pregnancy outcome, such as diabetes, hypertension, thyroid disorders, or infections. Maternal disease may increase the risk of miscarriage in later stages of pregnancy or cause other complications such as preterm labor or preeclampsia.

Choice A: 28 weeks' gestation is too early to screen for group B streptococcus infection. Group B streptococcus (GBS) is a type of bacteria that can cause serious infections in newborns if transmitted from the mother during labor and delivery. The optimal time to screen for GBS is between 35 and 37 weeks' gestation.

Choice B: 32 weeks' gestation is also too early to screen for GBS infection. Screening at this time may not reflect the true colonization status of the mother at the time of delivery, as GBS can be transient or intermittent.

Choice C: 16 weeks' gestation is much too early to screen for GBS infection. Screening at this time has no clinical value, as GBS colonization can change throughout pregnancy.

Choice D: 36 weeks' gestation is the appropriate time to screen for GBS infection. Screening at this time can identify mothers who are colonized with GBS and who need intrapartum antibiotic prophylaxis to prevent neonatal sepsis, pneumonia, and meningitis.