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The effect of maternal subclinical hypothyroidism on IQ in 7‐ to 8‐year‐old children: A case–control review
Author(s) -
Murphy Niamh C.,
Diviney Mairead M.,
Donnelly Jennifer C.,
Cooley Sharon M.,
Kirkham Colin H.,
Foran Adrienne M.,
Breathnach Fionnuala M.,
Malone Fergal D.,
Geary Michael P.
Publication year - 2015
Publication title -
australian and new zealand journal of obstetrics and gynaecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.734
H-Index - 65
eISSN - 1479-828X
pISSN - 0004-8666
DOI - 10.1111/ajo.12338
Subject(s) - intelligence quotient , wechsler adult intelligence scale , subclinical infection , pediatrics , pregnancy , medicine , confidence interval , case control study , cohort , comprehension , cognition , psychology , audiology , developmental psychology , clinical psychology , psychiatry , linguistics , philosophy , biology , genetics
Background In Ireland, pregnant women are not routinely screened for subclinical hypothyroidism ( SCH ). Aim Our objective was to compare the intelligence quotient ( IQ ) of children whose mothers had been diagnosed with SCH prenatally with matched controls using a case–control retrospective study. Materials and Methods In a previous study from our group, 1000 healthy nulliparous women were screened anonymously for SCH . This was a laboratory diagnosis involving elevated TSH with normal fT 4 or normal TSH with hypothyroxinaemia. We identified 23 cases who agreed to participate. These were matched with 47 controls. All children underwent neurodevelopmental assessment at age 7–8. Wechsler Intelligence Scale for Children IV assessment scores were used to compare the groups. Our main outcome measure was to identify whether there was a difference in IQ between the groups. Results From the cohort of cases, 23 mothers agreed to the assessment of their children as well as 47 controls. The children in the control group had higher mean scores than those in the case group across Verbal Comprehension Intelligence, Perceptual Reasoning Intelligence, Working Memory Intelligence, Processing Speed Intelligence and Full Scale IQ . Mann–Whitney U ‐test confirmed a significant difference in IQ between the cases (composite score 103.87) and the controls (composite score 109.11) with a 95% confidence interval (0.144, 10.330). Conclusions Our results highlight significant differences in IQ of children of mothers who had unrecognised SCH during pregnancy. While our study size and design prevents us from making statements on causation, our data suggest significant potential public health implications for routine prenatal screening.