Will hypothyroidism affect my twin fetuses?

Q: I am 32 years old and 17 weeks pregnant with twins, through the ICSI procedure. I was having thyroid problem prior to conception, and am still taking 100 mg of thyroxine. I recently repeated the test and my thyroid levels are: T3 is 267.6 ng/dl, T4 is 17.3 microg/dl and TSH is 3.80 microIU/ml. The laboratory has recommended for free T3 and T4 estimation. Can my present thyroid levels harm my fetuses? Is the dosage of thyroxine okay?

A:Hypothyroidism in pregnant women has several consequences for fetuses and infants including early pregnancy loss, pre-eclampsia, placental abruption, low birth weight (likely a result of preterm delivery for pre-eclampsia), perinatal mortality and neuropsychological impairment (which may occur even in women with subclinical hypothyroidism). But if hypothyroidism is treated properly, then there should not be a problem. Your TSH levels are almost within normal limit. Target TSH should be around 0.5-2. So, based on the next test your thyroxine can be increased by 10-15% to reach target TSH of around 0.5 to 2 thyroid function test during pregnancy.I do not think you should have problems as long as previous thyroid tests have been in similar range.