[1] Thyroid disorders are prevalent in women of child-bearing age and for this reason commonly present as a pre-existing disease in pregnancy, or after childbirth.
[1] The deleterious effects of thyroid dysfunction can also extend beyond pregnancy and delivery to affect neurointellectual development in the early life of the child.
[citation needed] Several studies, mostly retrospective, have shown an association between overt hypothyroidism and adverse fetal and obstetric outcomes (e.g. Glinoer 1991).
[11] Maternal complications such as miscarriages, anaemia in pregnancy, pre-eclampsia, abruptio placenta and postpartum haemorrhage can occur in pregnant women with overt hypothyroidism.
[15] Another study showed a higher prevalence of subclinical hypothyroidism in women with pre-term delivery (before 32 weeks) compared to matched controls delivering at term.
Also, a prospective intervention trial study showed that treatment of euthyroid antibody positive pregnant women led to fewer rates of miscarriage than non treated controls.
[17] It has long been known that cretinism (i.e. gross reduction in IQ) occurs in areas of severe iodine deficiency due to the fact that the mother is unable to make T4 for transport to the fetus, particularly in the first trimester.
This neurointellectual impairment (on a more modest scale) has now been shown in an iodine sufficient area (USA) where a study showed that the IQ scores of 7- to 9-year-old children, born to mothers with undiagnosed and untreated hypothyroidism in pregnancy, were seven points lower than those of children of matched control women with normal thyroid function in pregnancy.
Once pregnancy is confirmed the thyroxine dose should be increased by about 30-50% and subsequent titrations should be guided by thyroid function tests (FT4 and TSH) that should be monitored 4-6 weekly until euthyroidism is achieved.
Thyroxine requirements may increase in late gestation and return to pre-pregnancy levels in the majority of women on delivery.
Pregnant patients with subclinical hypothyroidism (normal FT4 and elevated TSH) should be treated as well, since supplementation with levothyroxine in such cases results in a significantly higher delivery rate, with a pooled relative chance of 2.76.
Distinctive clinical features of Graves' disease include the presence of ophthalmopathy, diffuse goitre and pretibial myxoedema.
A recent study has also shown that already high normal maternal FT4 levels are associated with a decrease in child IQ and gray matter and cortex volumes, similar to the effects of hypothyroidism.
[30] Surgery is considered for patients who have severe adverse reactions to anti-thyroid drugs and this is best performed in the second trimester of pregnancy.
On occasion, Carbimazole is associated with skin and also mid-line defects in the fetus but propylthiouracil long term also can cause liver side effects in the adult.
[31][needs update] There are no adverse effects on IQ or psychomotor development in children whose mothers have received antithyroid drugs in pregnancy.
This marker can be a useful screening test in early pregnancy as 50% of women with antibodies will develop thyroid dysfunction postpartum.