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Copyright ©The Author(s) 2016.
World J Obstet Gynecol. Feb 10, 2016; 5(1): 66-72
Published online Feb 10, 2016. doi: 10.5317/wjog.v5.i1.66
Table 1 Recommended values of thyroid stimulating hormone for each trimester
First trimester0.1-2.5 mIU/L
Second trimester0.2-3.0 mIU/L
Third trimester0.3-3.0 mIU/L
Table 2 Studies of subclinical hypothyroidism in pregnancy
Ref.DesignMethodResultConclusion
Pop et al[23], 1999Cohort study220 children were evaluated at 10 mo of age. Maternal TSH, FT4 and TPO antibodies were measured at 12 and 32 wk of pregnancyChildren of women with FT4 levels less than the 5th and 10th centiles at 12 wk had lower scores on the Bayley Psychomotor Development Index at 10 mo. No differences were found at 32 wkFT4 < 10% ile at 12 wk is a risk factor for impaired psychomotor development in offspring
Haddow et al[7], 1999Retrospective62 women with high TSHChildren of these women did less well on 15 tests of intelligence. Average decrease in IQ was 4 pointsUndiagnosed hypothyroidism adversely affects the fetal neurodevelopment
Henrichs et al[8], 2010Population based cohortWomen with normal TSH and FT4 < 5th and 10th centile. Expressive vocabulary of children was evaluated by mother at 18 and 30 moMaternal TSH not related to outcome. Both mild and severe low FT4 associated with higher risk of expressive language delay at all ages. Severe had higher risk of nonverbal cognitive delayMaternal low FT4 is a risk factor for early childhood cognitive delay
Lazarus et al[11], 2012Randomized prospectiveWomen in screening group were tested and treated Women in the control group had stored samples which were tested after delivery and received no treatment during pregnancyNo difference in cognitive function between the two groups at 3 yr of ageScreening and treatment for hypothyroidism did not improve neurodevelopmental outcomes in the offspring
Ghassabian et al[24], 2014Cohort3727 mother-child pairs with prenatal thyroid fxn tests before 18 wk. FT4 < 5% of normal. MRI of childrens brains and IQ test at age 6 yrChildren of mothers with low FT4 scored 4.3 points lower on nonverbal IQ test. No morphologic difference by MRIMaternal hypothyroxinemia has adverse effect on children’s non-verbal IQ at school age
Chen et al[13], 2015Prospective106 babies born to mothers with SCH and 106 babies born to euthyroid mothersBabies from both groups had similar scores on the Gesell development testNo neurodevelopmental deficit detected up to 24 mo in babies of mothers with SCH
Table 3 Diagnosis and treatment of thyroid disease in pregnancy
TSHFT4FT3RxGoal of treatment
HypothyroidLevothyroxine starting dose 1-2 mcg/kg dailyKeep TSH normal range
HyperthyroidPTU 50-150 mg TID in first trimester methimazole 10-40 mg BID or TID after first trimesterKeep FT4 high normal “watch for agranulocytosis”
Table 4 Six steps for treatment of thyroid storm
1 Admit to intensive care unitIV fluids and watch electrolytes
2 Tylenol 650 mg q6 hFor hyperpyrexia
3 Loading dose of 1000 mg PTU orally then 200 mg orally q6 h; alternate dosing 300 mg PTU q6 hWill block synthesis of T3 and T4
4 Iodine supplementation 10 drops of Lugol’s solution q8 h OR 1 g sodium Iodide IV q8-12 h Iodine allergy use lithium carbonate 300 mg PO q6 hBlocks release of hormone from the thyroid gland
5 Hydrocortisone 50-80 mg q8 h for 3 doses OR Dexamethasone 2 mg IV q6 h for 4 dosesTo block peripheral conversion of T4 to T3
6 Beta blocker Labetolol 300 mg TID may increase to a max dose of 800 mg TID but watch blood pressureTo control the tachycardia – use cautiously in heart failure
Table 5 Frequency of antenatal surveillance
UltrasoundAntenatal testing (Nonstress test or Biophysical Profile)
HyperthyroidMonthlyTwice weekly if poorly controlled
HypothyroidNo recommendation Consider monthlyNo recommendation