pH of amniotic fluid at later weeks of gestation :
**Core Concept**
During pregnancy, the pH of amniotic fluid is a vital indicator of fetal well-being. The amniotic fluid pH is maintained by the balance of fetal urine production, maternal-fetal exchange, and the presence of various buffers. A slight alkalosis in the amniotic fluid is considered normal, which helps in maintaining the optimal pH for fetal development.
**Why the Correct Answer is Right**
The pH of amniotic fluid is slightly alkaline, ranging from 7.10 to 7.30, during the later weeks of gestation. This alkaline pH is primarily maintained by the presence of bicarbonate ions (HCO3-) and the buffering capacity of the amniotic fluid. The fetal kidneys produce a significant amount of bicarbonate ions, which helps in maintaining the alkaline pH of the amniotic fluid. Additionally, the exchange of ions and fluids between the mother and fetus also contributes to the maintenance of the optimal pH.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the pH of amniotic fluid is not acidic. An acidic pH would indicate fetal distress or other complications.
**Option B:** This option is incorrect because the pH of amniotic fluid is not neutral. A neutral pH would imply a lack of buffering capacity, which is not the case in the amniotic fluid.
**Clinical Pearl / High-Yield Fact**
It is essential to remember that the pH of amniotic fluid is a critical parameter in assessing fetal well-being. A pH outside the normal range can indicate fetal distress or other complications, necessitating prompt medical attention.
**Correct Answer: C. 7.10-7.30**