In a population-based cohort study reported online in JAMA Psychiatry, researchers at Karolinska Institute in Stockholm, Sweden, found an association between maternal body mass index (BMI) and weight gain in pregnancy and the offspring’s risk for psychosis.1
Key historical events involving prenatal exposure to famine, such as the Dutch Hunger Winter and the Chinese Great Leap Forward in the mid-20th century, have been linked to a 2-fold increase in the offspring’s risk of developing nonaffective psychosis, and previous research has found connections between maternal nutritional deficits and the psychosis risk of offspring.2,3 The current study examined the relationship between maternal baseline BMI, gestational weight gain (GWG), and the risk for nonaffective psychosis in offspring.
The authors used the Swedish Health and Population Registers to collect data on 526,042 patients (48.52% women). They expected to find that extremes in either weight-based measure would reflect poor prenatal nutrition and thus contribute to the offspring’s nonaffective psychosis risk. To further elucidate the potentially causal nature of any findings, they also used paternal/offspring comparisons and matched-sibling comparisons.
The analysis revealed the following associations at the end of the follow-up period:
- 2910 individuals in the sample had nonaffective psychoses, including 704 with narrowly defined schizophrenia.
- 6.32% of individuals with nonaffective psychosis had mothers with GWG that was considered extremely inadequate vs 4.52% of individuals without nonaffective psychosis.
- Extremely inadequate GWG was linked to higher risk for nonaffective psychoses in offspring (hazard ratio [HR], 1.32; 95% CI, 1.13-1.54), as well as in matched-sibling comparisons (HR, 1.61; 95% CI, 1.02-2.56).
- Similar patterns were found for narrowly defined schizophrenia.
- A weak association was found between maternal mild thinness in early pregnancy and an increased risk for nonaffective psychosis in offspring (HR for BMI ≥17.0 and <18.5 kg/m2, 1.21; 95% CI, 1.01-1.45),
- A weak association was also noted for severe paternal thinness (HR for BMI <16.0 kg/m2, 2.53; 95% CI, 1.26-5.07).
- Matched-sibling analysis showed no association between maternal underweight (HR, 1.46; 95% CI, 0.90-2.35), overweight (HR, 1.11; 95% CI, 0.73-1.68), or obesity (HR, 0.56; 95% CI, 0.23-1.38) and offspring’s risk for nonaffective psychosis in offspring.
“Extremely inadequate GWG was associated with an increased risk for nonaffective psychosis in offspring in categorical and continuous analyses, even after adjustment for potential confounders” such as birth year, household income at the time of birth, and single-parent household status, the authors summarized. Similar to earlier studies, these findings suggest that “inadequate maternal nutrition during pregnancy increases the risk for nonaffective psychosis in offspring, even in the context of an affluent and well-nourished population.”
- Mackay E, Dalman C, Karlsson H, Gardner RM. Association of gestational weight gain and maternal body mass index in early pregnancy with risk for nonaffective psychosis in offspring [published online February 22, 2017]. JAMA Psychiatry. doi: 10.1001/jamapsychiatry.2016.4257
- Hoek HW, Brown AS, Susser E. The Dutch famine and schizophrenia spectrum disorders. Soc Psychiatry Psychiatr Epidemiol. 1998;33(8):373-379. doi: 10.1007/s001270050068
- Xu M, Wang P, St Clair D, Xu M, Wang P. Rates of adult schizophrenia following prenatal exposure to the Chinese famine of 1959-1961. JAMA. 2005;294(5):557-562. doi: 10.1001/jama.294.5.557