Itching in pregnancy is commonly ignored as a normal effect of pregnancy induced changes in the body but is certainly not normal. It is the sign of intrahepatic cholestasis, the unique liver disease of pregnancy.
Cholestasis of pregnancy is an innocent self-limiting liver disorder as far as the mother is concerned, but a cause of several fetal complications. It usually begins towards the end of the second trimester of the first pregnancy and resolves spontaneously in the second or third week after childbirth.
Pregnancy hormones affect liver function. Of them, mainly estrogen hampers bile acids export out of their site of production, the liver cells. As a result, the accumulated bilirubin and bile acids are unable to flow out of the liver cells into tiny collecting ducts, the canaliculi. Instead, they spill into the bloodstream, and then through the placenta to the fetus. Bile acids and bilirubin, both are toxic to the fetus.
A single blood test, the mother's liver functions, is all that is required to clinch the diagnosis. Bile acids concentration of 10 μmol/L or above confirms intrahepatic cholestasis of pregnancy.
The increase in serum concentration of bile acids is the first, and often, the only abnormality noted. The blood test may, however, show generalized functioning disorder of the liver in the form of elevated liver enzymes - AspAt, AlAt, and GGTP.
Unaware of the danger high bile acids in mother's blood impose on fetal growth, most women don't even bring the only symptom they have to the notice of their doctor, itching in pregnancy - typically in hands and feet.
Pruritus, without any skin rash, is not the only symptom of cholestasis of pregnancy. There are many more. They all point towards compromised functioning of the liver, for example, poor appetite, indigestion, fatigue, light-colored stools, and slight yellow discoloration of eyes, skin, and urine. But they too get overshadowed by the discomforts of advanced pregnancy.
However, the signs and symptoms in the pregnant woman do not correlate with the severity of fetal complications.
High bile acids in mother's blood endanger the fetus. The gravity of fetal complications correlates well with the bile acids level in the mother's blood.
Serum bile acids level above 10 μmol/L in women with cholestasis of pregnancy increases the risks of overall adverse perinatal outcomes. And, if it rises above 100 μmol/L or more, the chances of sudden intrauterine fetal death increase by several folds, that too just before birth, or during the birth process itself. Nevertheless, in a large number of the cases with bile acids concentration between 10 and 40 μmol/l, the fetus may remain unharmed.
The same does not hold true when the blood bile acids level rise above 40 μmol/l. Beyond 40 μmol/l, the magnitude of the risk to the baby's well being, and its need for intensive neonatal care is directly proportional to the mother's bile acid levels.
Almost 2 in 15 infants born to mothers with intense itching in pregnancy require to be cared for in the newborn care unit for inadequate fetal growth, premature birth, fetal distress, falling frequency of fetal heartbeats, presence of meconium in the amniotic fluid, respiratory distress syndrome, or birth asphyxia.
Exactly how cholestasis of pregnancy causes fetal complications is yet not quite clear. It all translates into bile acid toxicity. A high concentration of bile acids in fetal blood aggravates the activity of almost all smooth muscles.
Click here to know more on bile acids that cause itching in pregnancy and devastating fetal complications. - scroll down a little. On your right hand side you will find the link for the video "Overview of Cholestasis" - watch it, and have a clear picture on what goes on inside the liver.
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