Most common cause of intrauterine infection
**Core Concept**
Intrauterine infections occur when pathogens breach the fetal-maternal interface, leading to infection and potential harm to the fetus. The most common causes of intrauterine infections are related to bacterial vaginosis and group B streptococcal colonization in the mother.
**Why the Correct Answer is Right**
Group B streptococcus (GBS) is a gram-positive bacterium that commonly colonizes the gastrointestinal and genitourinary tracts of healthy adults, including pregnant women. When GBS enters the uterus, it can cause chorioamnionitis, leading to preterm labor, fetal distress, and potentially life-threatening complications. GBS infection is a leading cause of neonatal sepsis and mortality worldwide.
**Why Each Wrong Option is Incorrect**
**Option A:** Bacterial vaginosis is a common cause of postpartum endometritis but is not the most common cause of intrauterine infection.
**Option B:** Candida albicans is a common cause of vulvovaginal candidiasis but is less commonly associated with intrauterine infection compared to GBS.
**Option C:** Herpes simplex virus (HSV) can cause congenital infection, but it is relatively rare compared to GBS.
**Clinical Pearl / High-Yield Fact**
To minimize the risk of GBS transmission to the fetus, pregnant women are screened for GBS colonization at 35-37 weeks of gestation, and those who are colonized may receive intrapartum antibiotic prophylaxis.
**Correct Answer: D. Group B streptococcus**