Study Methods
Publications under ‘Study Methods’ explain and describe the components and populations of both PRESTO and our Danish study “Snart Gravid”
This paper summarizes the study design and data collection of the Boston University Pregnancy Study Online (PRESTO). In the first two years (2013-2015), 2,421 women and 693 male partners in the US and Canada enrolled in PRESTO.
This article describes the methods of cohort recruitment and follow-up in our “sister” Danish Web-based Pregnancy Planning Study (“Snart Gravid”).
In the Danish Web-based Pregnancy Planning Study (“Snart Gravid”), we randomly assigned participants to receive a longer or shorter version of the same questionnaire at enrollment. Enrollment rates were similar for both versions.
After the first year of the Danish Web-based Pregnancy Planning Study (“Snart Gravid”), we evaluated the feasibility and cost-effectiveness of the study. We found that the study was successful in recruiting and retaining participants, and it was cost-effective.
We compared the accuracy of reported time to pregnancy by reporting every 2 months while trying to conceive vs. by recall during the first trimester of pregnancy. The two methods had similar results.
We analyzed the associations between several risk factors and pregnancy outcomes in the Snart Gravid cohort and among all births in Denmark, using data from the National Danish Birth Registry. Similar associations were found, suggesting that selection bias is not likely to be a major problem in Snart Gravid.
We compared measurement of diet and nutritional intake using a web-based questionnaire vs. a four-day food diary. The web-based questionnaire performed well.
We compared the costs and efficiency of several methods of recruiting participants to the Danish Web-based Pregnancy Planning Study. Over 80% of participants were enrolled via various online recruitment methods, which had a lower average cost per participant compared with “offline” methods such as flyers and press releases.
This article describes the Preconception Period analysis of Risks and Exposures Influencing health and Development (PrePARED) consortium. Through the PrePARED consortium, PRESTO will work together with several other studies of preconception health to answer important research questions related to fertility and pregnancy.
In a randomized study, we sent home pregnancy tests to 50% of participants with ≤6 cycles of pregnancy attempt time. Receiving a home pregnancy test made participants more likely to stay in the study, but did not influence their fecundability or timing of pregnancy detection. This paper won ‘article of the year’ at the American Journal of Epidemiology in 2020.
We linked PRESTO participant data on birth outcomes to birth certificate data. Self- reported data on gestational age at delivery (in weeks) and birth weight (in grams) from PRESTO participants was shown to be highly accurate compared with what was listed on their birth certificate.
PRESTO researchers used machine learning methods to develop models that can predict pregnancy based on lifestyle, medical, and reproductive characteristics. Important predictors included female age, male and female BMI, a history of childbearing, and pre-pregnancy use of multivitamins or folate supplements.
We evaluated the feasibility and cost-effectiveness of in-clinic and mail-based biospecimen collection among study participants. During 1/2022-7/2022, 69% of female participants (134/195) and 42% of male participants (31/74) consented to participate in the mail-based protocol (inviting those residing across the United States). Consent rates for the in-clinic protocol (Detroit and Boston area participants only) were 39% for female participants (289/739 during 3/2014-7/2022) and 25% for male participants (40/157 during 3/2017-7/2022). Participants who consented to participate were generally of higher SES than non-participants. The cost per participant enrolled was similar across protocols (mail-based: $276.14 vs. in-clinic: $270.38). Our results indicate that mail-based collection of biospecimens may create opportunities to recruit a larger and more geographically diverse participant population at a comparable cost-per-participant enrolled to in-clinic methods.
We assessed the effect of randomization to FertilityFriend.com (FF), a fertility-tracking app, on fecundability (per-cycle probability of conception). Of those randomized to FF, 72% used the app (68% of observed menstrual cycles). In intent-to-treat analyses (where we studied randomized groups regardless of actual use), there was little association overall or within strata of pregnancy attempt time at enrolment, age, education, or other characteristics. In per-protocol analyses (where we considered actual use), we observed little association overall, but weak-to-moderate positive associations among participants who had longer attempt times at enrolment (Fecundability Ratio (FR) = 1.15 for 3-4 cycles; FR = 1.14 for 5-6cycles), were aged <25 years (FR = 1.29), had ≤12 years of education (FR = 1.32), or were non-users of hormonal contraception within 3 months before enrolment (FR = 1.10).
There was some evidence of reduced participant engagement after the Dobbs decision in states with banned or restricted abortion rights, indicating potentially deleterious effects on the conduct of reproductive health studies.
We compared nutrients measured by two versions of the Diet History Questionnaire (DHQ III vs. II), a food frequency questionnaire completed by PRESTO participants 30 days after enrollment in the study. Our results suggested differences in assessment for some nutrients across DHQ versions, including protein, total fat, monounsaturated fat, and vitamin D.
Our findings suggest that miscarriage is not easily predicted on the basis of preconception lifestyle characteristics and that advancing age and a history of miscarriage are the most important predictors of incident miscarriage.