TABLE 2—
Major Contributions of the Nurses’ Health Studies to Reproductive Health Research
| Area | Main Finding | References |
| Menstrual cycle irregularities | Women with irregular menstrual cycles are at increased risk for type 2 diabetes mellitus (2-fold) and CVD (53% increase). | 1, 2 |
| Fertility | Infertility associated with ovulation disorders is largely preventable. Nearly half of the cases (46%) could be attributed to poor diet alone, and the majority of cases (66%) could be attributed to poor diet, inactivity, and overweight. | 3, online appendix |
| Fertility | Occupational exposures specific to nursing are related to decreased fecundity. | Online appendix |
| Adverse pregnancy outcomes | Prepregnancy weight loss (particularly among overweight women) and supplemental folic acid intake above the recommended intake for prevention of neural tube defects is related to lower risk of spontaneous abortion and stillbirth. | 4, 5 |
| Adverse pregnancy outcomes | GDM is largely preventable. Nearly half of all cases of GDM (48%) could be attributed to poor diet, inactivity, overweight, and smoking. | 6, online appendix |
| Endometriosis | Incidence of endometriosis documented at earlier ages than previously reported and across demographic characteristics. This is the first study to evaluate risk factors for endometriosis specific to diagnostic phenotypes. | 7 |
| Endometriosis | This is the first prospective cohort study able to study risk factors for this condition, and the first study to identify a relation between in utero exposures as well as growth trajectories across the life course and endometriosis risk. | 8–10 |
| Endometriosis | This is the first study to identify modifiable risk factors including diet, lactation, physical activity, air pollution exposure, and rotating shiftwork. | 11, online appendix |
| Uterine leiomyomata | This is the first study to prospectively document the direct relation between age and incidence among premenopausal women and the 3-fold increase for Black women compared with White women. | 12 |
| Uterine leiomyomata | This study demonstrated critical life course relationships between risk and reproductive milestones including age at menarche, age at first exposure to oral contraceptives, and age at first and last birth. | 13, online appendix |
| Uterine leiomyomata | This is the first prospective study to confirm linear relation between blood pressure and risk of uterine leiomyomata, regardless of antihypertensive therapy, and with history of stress related to abuse or other acute or chronic exposures. | 14, online appendix |
| Reproductive events and chronic disease | The association between birth weight and risk of CVD cannot be explained by socioeconomic conditions, smoking, diet, family history, and other risk factors for CVD. | 15 |
| Reproductive events and chronic disease | Women who experience pregnancies complicated by GDM or who deliver preterm are at increased risk for type 2 diabetes and hypertension later in life. | 16–18 |
| Reproductive events and chronic disease | A healthy diet, weight control, and increased physical activity can decrease the risk of type 2 diabetes among women with a history of GDM. | 19–22 |
| Reproductive events and chronic disease | Women with endometriosis are at increased risk for CVD, systemic lupus erythematosus, and rheumatoid arthritis. | 23, 24 |
| Reproductive events and chronic disease | Undergoing infertility treatment is not related to later risk of hypertension in the woman or to risk of autism spectrum disorders in the offspring. | 25, 26 |
Note. CVD = cardiovascular disease; GDM = gestational diabetes mellitus. Appendix available as a supplement to the online version of this article at http://www.ajph.org.