Open Access Highly Accessed Open Badges Research article

Folic acid supplementation before and during pregnancy in the Newborn Epigenetics STudy (NEST)

Cathrine Hoyo1*, Amy P Murtha2, Joellen M Schildkraut1, Michele R Forman3, Brian Calingaert1, Wendy Demark-Wahnefried4, Joanne Kurtzberg5, Randy L Jirtle6 and Susan K Murphy7

Author Affiliations

1 Department of Community and Family Medicine and Program of Cancer Detection, Prevention and Control, Duke University, PO Box 104006, Durham, NC 27710, USA

2 Department of Obstetrics and Gynecology, Division of Maternal-Fetal Medicine, Duke University, 4022 Hospital South, Durham, NC 27710, USA

3 Department of Epidemiology, MD Anderson Cancer Center, 1515 Holcombe Blvd., Unit 1340, Houston, TX 77030-4009, USA

4 Department of Behavioral Science, MD Anderson Cancer Center, 1515 Holcombe Blvd., Unit 1340, Houston, TX 77030-4009, USA

5 Department of Pathology and Carolinas Cord Blood Banking Project, Duke University, 1430 N. Pavilion Bldg, Durham, NC 27705, USA

6 Department of Radiation Oncology, 139 Env Safety Bldg., Durham, NC 27710, USA

7 Department of Obstetrics and Gynecology, Division of Gynecologic Oncology, Department of Pathology Duke University, 226 B Wing LSRC Research Drive Durham, NC 27708, USA

For all author emails, please log on.

BMC Public Health 2011, 11:46  doi:10.1186/1471-2458-11-46

Published: 21 January 2011



Folic acid (FA) added to foods during fortification is 70-85% bioavailable compared to 50% of folate occurring naturally in foods. Thus, if FA supplements also are taken during pregnancy, both mother and fetus can be exposed to FA exceeding the Institute of Medicine's recommended tolerable upper limit (TUL) of 1,000 micrograms per day (μg/d) for adult pregnant women. The primary objective is to estimate the proportion of women taking folic acid (FA) doses exceeding the TUL before and during pregnancy, and to identify correlates of high FA use.


During 2005-2008, pre-pregnancy and pregnancy-related data on dietary supplementation were obtained by interviewing 539 pregnant women enrolled at two obstetrics-care facilities in Durham County, North Carolina.


Before pregnancy, 51% of women reported FA supplementation and 66% reported this supplementation during pregnancy. Before pregnancy, 11.9% (95% CI = 9.2%-14.6%) of women reported supplementation with FA doses above the TUL of 1,000 μg/day, and a similar proportion reported this intake prenatally. Before pregnancy, Caucasian women were more likely to take FA doses above the TUL (OR = 2.99; 95% = 1.28-7.00), compared to African American women, while women with chronic conditions were less likely to take FA doses above the TUL (OR = 0.48; 95%CI = 0.21-0.97). Compared to African American women, Caucasian women were also more likely to report FA intake in doses exceeding the TUL during pregnancy (OR = 5.09; 95%CI = 2.07-12.49).


Fifty-one percent of women reported some FA intake before and 66% during pregnancy, respectively, and more than one in ten women took FA supplements in doses that exceeded the TUL. Caucasian women were more likely to report high FA intake. A study is ongoing to identify possible genetic and non-genotoxic effects of these high doses.