Maternal Health in Pregnancy and Intellectual Disability in the Offspring: A Population-Based Study

https://doi.org/10.1016/j.annepidem.2005.05.002Get rights and content

Purpose

The aim of the study is to investigate the relationship between common maternal conditions and intellectual disability (ID) of unknown cause in the offspring.

Methods

Information about the maternal health of children with and without ID was obtained by using record linkage. For mothers with specific medical conditions, proportions of children with mild to moderate ID, severe ID, and autism spectrum disorder (ASD) with ID were compared with those who did not have ID.

Results

There was an increased risk for mild to moderate ID in children of mothers with asthma (odds ratio [OR], 1.52; confidence interval [CI], 1.26–1.83]), diabetes (OR, 1.69; CI, 1.26–2.27), a renal or urinary condition (OR, 2.09; CI, 1.39–3.14), and epilepsy (OR, 3.53; CI, 2.56–4.84). ASD risk was increased for children of women with diabetes (OR, 2.89; CI, 1.28–6.51) and epilepsy (OR, 4.57; CI, 1.69–12.31). For anemia (n = 1101), there was an increased risk for severe ID (OR, 5.26; CI, 2.16–12.80).

Conclusions

The increased risk for ID in offspring of mothers with such conditions as asthma and diabetes is particularly important for disadvantaged or ethnic populations, for whom these conditions are more prevalent and may be less well managed.

Introduction

People with intellectual disability (ID) have significant cognitive impairment and limitations in adaptive skills, manifesting before 18 years of age. The most recent definition by the American Association on Mental Retardation requires impairment of intellectual functioning, defined by an IQ score in the range of 70 to 75 or less, coexisting with limitations in two or more areas of adaptive skills (1). However, the definition and classification of level of ID varies among countries (2).

Specific maternal illnesses, conditions, and treatments result in adverse neurodevelopmental outcomes in offspring. Congenital infections, such as cytomegalovirus and rubella, may result in ID in the child 3, 4. Recent evidence also suggests that maternal urinary tract infection may be associated with an increased risk for ID 5, 6, 7. The cognitive outcome of children may be affected directly by the level of metabolic control in pregnancies of women with phenylketonuria (8). Maternal thyroid deficiency also was shown to affect adversely the neuropsychological development of offspring, even when hypothyroidism is mild and asymptomatic (9). Maternal diabetes in pregnancy may be detrimental to a child's neurodevelopment (10), whereas maternal epilepsy and exposure of the fetus to antiepileptic drugs (AEDs) also can be associated with developmental problems (11). However, in at least half the children with ID, particularly those with mild or moderate ID, there is no known cause, although factors affecting neurodevelopmental outcome are likely to be multifaceted (12).

Most previous research on maternal health and neurodevelopmental outcomes in children tended to focus on specific individual maternal conditions, rather than the contribution of maternal conditions considered together to the burden of ID in the community. In the present study, we look at association between common maternal conditions and ID of unknown cause in offspring within the total population of Western Australia (WA) by using linked data sets. We (13) and others 5, 14 also showed a clear inverse socioeconomic gradient associated with ID. Because some maternal conditions also may be associated with socioeconomic factors 15, 16, 17, we adjusted for them in the analysis.

Section snippets

Methods

WA is the largest state in geographic area in Australia, and ascertainment of ID from multiple sources, including agencies providing general, medical, and educational services, has been described previously (18). There were 3387 children born in WA between 1983 and 1992 and identified to have ID by 1999 through at least one of the services, whose births linked to their midwife-completed birth record (19) and who were alive in 2002. Children could be identified through the Disability Services

Results

The proportion of children with ID born to mothers with certain medical conditions and unadjusted ORs are listed in Table 1. The most common condition was asthma (n = 7751). Asthma affected 118 mothers (4.8%) of children with mild to moderate ID compared with 3.2% of mothers whose children did not have ID (OR, 1.52; CI, 1.26–1.83). The next most common condition was diabetes (including gestational diabetes, n = 2686). For these women, there was a significantly increased risk for mild to

Discussion

We found a modest increased risk for mild to moderate ID in children whose mothers had renal or urinary conditions, asthma, and diabetes (ORs, 1.23 to 1.65) and a threefold increased risk for women with epilepsy. For women with anemia, we found a fivefold risk for having a child with severe ID. Despite relatively small numbers of cases, we also found an increased risk for having a child with ASD associated with ID for women with diabetes (threefold) and epilepsy (nearly fivefold). There also is

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