Most common cause of low birth wt baby is
**Core Concept**
Preterm birth, also known as low birth weight (LBW), is a significant public health concern worldwide. It is defined as a birth weight of less than 2,500 grams (5.5 pounds). The etiology of preterm birth is multifactorial, involving a combination of maternal, fetal, and environmental factors.
**Why the Correct Answer is Right**
The most common cause of preterm birth is preterm labor, which is the onset of labor before 37 weeks of gestation. This can be precipitated by various factors, including cervical insufficiency, uterine anomalies, and multiple gestations. Cervical insufficiency refers to a condition where the cervix is unable to maintain the pregnancy, leading to premature dilation and effacement. This can be due to a variety of causes, including cervical trauma, previous uterine surgery, or congenital anomalies.
**Why Each Wrong Option is Incorrect**
**Option A:** Intrauterine growth restriction (IUGR) is a condition where the fetus does not grow at a normal rate inside the womb. While IUGR can be associated with low birth weight, it is not the most common cause of preterm birth.
**Option B:** Placental abruption is a condition where the placenta separates from the uterus, leading to fetal distress and possible preterm birth. However, it is not the most common cause of preterm birth.
**Option C:** Maternal infection is a risk factor for preterm birth, but it is not the most common cause. Infections such as group B strep and chorioamnionitis can trigger preterm labor, but they are not the primary cause.
**Clinical Pearl / High-Yield Fact**
A key factor in the prevention of preterm birth is the identification of women at high risk. This includes those with a history of previous preterm birth, multiple gestations, and cervical insufficiency. Early prenatal care and regular cervical length assessments can help identify women at risk and allow for timely intervention.
**Correct Answer: D. Preterm labor**