During the course of research for a book on coeliac disease (CD), I conducted an online survey among New Zealand women with CD to examine their experiences of fertility, pregnancy and births. Invitations were sent out in November 2016 by Coeliac New Zealand via their email newsletters and Facebook page. Two hundred and sixty women responded to the survey, of whom 200 had biopsy-proven CD. Median age at CD diagnosis was 33 years (range 2–80 years).

Respondents were asked if they had had, or tried to have, a baby before they were diagnosed with CD; 65 had been diagnosed before trying to have a baby, and 133 people were diagnosed after trying to start their family. Two people did not answer this question. Groups were compared using a 2-sample t-test for categorical analysis of proportions. For other variables, a linear regression model or log-linear regression model was used to compare groups, with “diagnosed after trying to get pregnant” as the dependent variable.

Results are shown in Table 1. Women who were diagnosed with CD before trying to become pregnant had a significantly higher number of pregnancies and live births compared with women who were diagnosed earlier, possibly because of differences in age between the two groups. Women diagnosed with CD after starting a family were significantly more likely to have had a miscarriage (45% vs 19%) and had on average more miscarriages per person (1.6 vs 1.2) compared with those who had been diagnosed prior to trying to get pregnant. However, the rate of miscarriage in the two groups was not significant after adjusting for differences in the number of pregnancies (P=0.886). Although a higher proportion of women diagnosed with CD after vs before trying to start a family sought medical advice about conception difficulties, the between group difference was not statistically significant. The group diagnosed with CD after trying to start a family also had a significantly increased incidence of a premature delivery (19.4% vs 3.4%), and the incidence of preterm delivery in late diagnosed women was higher than the New Zealand average of 7.3%.1 However, after adjustment for between-group differences in the number of pregnancies, the difference in the rate of premature delivery among women diagnosed later vs earlier was of borderline statistical significance (P=0.0678).

Table 1: Pregnancy and birth results in women who were diagnosed with CD before and after trying to start a family.

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*Live birth at <37 weeks’ gestation.
aPercentages are based on the number of responses to a specific question

This research is limited in a number of ways. First, surveys are subject to recall and response bias, and I did not survey women without CD as a control group. Second, the two groups were not comparable in age, which could have affected pregnancy and miscarriage rates since these are known to be affected by age. Third, the survey did not capture information about the timing of CD treatment in relation to pregnancy. Even assuming that all participants followed the recommended gluten-free diet after their CD diagnosis, it may take years for CD patients to achieve mucosal healing and correction of body composition abnormalities.2

Despite these limitations, the findings suggest that undiagnosed CD may contribute to worse pregnancy outcomes. This is consistent with case-control studies showing that pregnancy outcomes can be affected by undiagnosed CD.3–10 In these studies, undiagnosed CD was most commonly associated with intrauterine growth retardation and low birth weight,4,5,8,9 and to a lesser extent miscarriage,3,7,11 whereas diagnosed CD was not.3,4 According to one study, undiagnosed CD increases the risk of having a small for gestational age infant by 7-fold.8 Some of the women in this survey had been pregnant before and after their CD diagnosis, and reported having small and early babies before their diagnosis, but bigger babies closer to term after their diagnosis. Based on the previous literature and the current findings in a large cohort of New Zealand women, it would seem prudent to screen pregnant women for CD in New Zealand, especially since CD is particularly common in women of childbearing age,12 and arguably more prevalent than some of the other conditions which are now part of the standard pregnancy screening panel.

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