In this research, the authors sought to answer whether there was a link between potato consumption before pregnancy and the risk of developing gestational diabetes. The condition is also known as pregnancy-induced diabetes, and affects as much as 9% of all pregnancies.
Researchers collected self-reported data from 15,632 women who were part of the Nurses’ Health Study II and who became pregnant over a 10-year period (1991-2001). These women had no history of gestational diabetes or other chronic health conditions. Every four years, the women filled out self-reported questionnaires of food consumptions. Any reported diagnoses of gestational diabetes were then validated with medical records.
During the 10-year follow-up, the researchers found 854 cases of gestational diabetes occurred in the total 21,693 single-birth pregnancies. After adjusting for age, family history, overall diet, BMI, and other risk factors, researchers still see a link between potato consumption and risk for gestational diabetes.
The study further outlined that consuming 2-4 servings of potatoes per week pre-pregnancy increased the risk of gestational diabetes by 27%. This risk increases to 50% when potato consumption exceeds 5 cup serving of potatoes per week.
But before we lambaste potatoes completely, it’s important to note the limitations of the study and why the results aren't as extreme as it sounds.
The biggest limitation here is that all the data that were used to draw conclusions for this study were based on self-reported assessments. There are many ways in which a questionnaire can bias how a participant responds. And this study’s questionnaire had an inherent bias towards potato consumption, possibly swaying the participants’ answers.
Even when questionnaires are perfectly designed to be completely unbiased, the participants’ responses are subject to recall biases. These are errors in retrieving past memories, and can dramatically skew data results. It is not unlikely that participants in this study suffered from recall bias, as the questionnaires were answered at four-year intervals.
And finally, even if researchers were able to adjust for all the biases inherent in this type of study design, the study does not prove a cause-and-effect relationship between potatoes and gestational diabetes. In their own words, the authors say that “a causal association cannot be assumed.”
So, pre-pregnant women don’t have to forgo potatoes entirely. But they also shouldn’t consume the tubers without limits either.
Potatoes have a higher glycemic index than other vegetables, thus can trigger sharp rises in blood sugar levels. Ultimately, pregnant or not, moderation is probably best when it comes to these delicious starchy treats.
Additional source: Medline Plus