Maternal recall of breastfeeding duration by elderly women.

Studies of long-term effects of breastfeeding on the health of both infants and mothers often rely on maternal recall of breastfeeding duration after several decades. The authors evaluated this recall by 140 college-educated, US women 69-79 years of age who breastfed a child in 1940-1956 and recorded the duration both prospectively in a diary for the Menstruation and Reproductive History Study and retrospectively in a questionnaire in 1990-1991. Mean prospective breastfeeding duration was 5.6 months (range, 1-12 months). Mean reporting difference, questionnaire minus diary duration, was 0.0 months, with a standard deviation of 2.7 months; women who recorded short durations tended to overreport, while women who noted long durations underreported. The weighted kappa statistic for reporting agreement was 0.55 (95% confidence interval: 0.42, 0.67), with better recall observed for women in the youngest quintile at recall, firstborns, and infants with more siblings. Ever having breastfed was recalled by 94% of women. For categories of 1-3, 4-6, 7-9, and 10-12 months, recalled breastfeeding duration was correctly classified by 54% of women and was classified within +/-1 category by 89%. The observed misclassification, if nondifferential with respect to outcome, would appreciably attenuate estimates of dose-response associations between breastfeeding duration and later health.

Bed rest and other determinants of bone loss during pregnancy.

OBJECTIVE: The purpose of this study was to evaluate patterns of bone loss during pregnancy and potential influences. STUDY DESIGN: This was a prospective study of 181 women receiving prenatal care at Magee-Womens Hospital or its auxiliary clinics in Pittsburgh, Pennsylvania, between 1992 and 1995. Bone mineral density was measured at approximately 16 and 36 weeks' gestation. RESULTS: Trabecular, but not cortical, bone loss occurred during pregnancy. Mean ultra-distal bone mineral density loss was 1.9% (95% CI 1.2-2.5) during the 20-week period. Women prescribed bed rest had an adjusted mean loss of 4.6% compared with 1.5% for women not prescribed bed rest ( P = .001) and 6-fold higher odds ( P = .001) of bone loss > or =5% during the 20-week period. Nulliparity, calcium intake < 2 000 mg/day, low weight gain, and maternal age < 21 or >30 years were more modestly associated with greater bone loss. CONCLUSION: Substantial trabecular bone loss may occur during pregnancy, particularly in women prescribed bed rest. Study of postpartum bone recovery in such women is needed.

Recruitment for a community-based study of early pregnancy: the Right From The Start study.

Despite the high incidence of spontaneous abortion, little is known about its causes, in part because of the challenge of assembling a large cohort of women in early pregnancy for prospective study. We describe the effectiveness of recruitment strategies used in Right From The Start (RFTS), a prospective, community-based study of spontaneous abortion. Between December 2000 and September 2002, 803 pregnant women enrolled in RFTS, 103 of whom were recruited while trying to conceive. The mean gestational age at enrollment was 52 days, with 25% of the cohort enrolling before 6 completed weeks' gestation. Participants recruited directly from the community typically enrolled earlier in their pregnancies (mean of 44 days) and accounted for 24% of the total cohort and 83% of all participants who were recruited while trying to conceive. Posting brochures in drug stores and targeted mailings to new homeowners were the most effective community recruitment strategies. Recruitment at private and public prenatal care sites accounted for 57% and 19% of the participants respectively. Recruitment from public clinics required direct contact by RFTS staff and yielded women who enrolled at later gestational ages (mean of 58 days), but was valuable for inclusion of minorities and lower income women with less favourable health behaviours. Although intensive, diverse efforts were required, when recruitment efforts were maximised, we successfully recruited over 10% of the estimated number of pregnant women in the community.

Vitamin C intake and the risk of preterm delivery.

OBJECTIVE: Ascorbic acid deficiency may lead to premature rupture of the membranes. STUDY DESIGN: The study included a prospective cohort of pregnant women, aged >/=16 years, with singleton gestations who received care at one of four prenatal clinics in central North Carolina from 1995 through 1998. Vitamin C intake preconceptionally and during the second trimester was examined for its association with preterm delivery and subsets of preterm labor, premature rupture of the membranes, and medical induction in 2064 women. RESULTS: Women who had total vitamin C intakes of <10th percentile preconceptionally had twice the risk of preterm delivery because of premature rupture of the membranes (relative risk, 2.2; 95% CI, 1.1, 4.5). This risk was attenuated slightly for second-trimester intake (relative risk, 1.7; 95% CI, 0.8, 3.5). The elevated risk of preterm premature rupture of the membranes was greatest for women with a low vitamin C intake during both time periods. CONCLUSION: Because diet and supplement use are modifiable behaviors, corroboration of these findings would suggest a possible intervention strategy.

Retinol intake and bone mineral density in the elderly: the Rancho Bernardo Study.

Retinol is involved in bone remodeling, and excessive intake has been linked to bone demineralization, yet its role in osteoporosis has received little evaluation. We studied the associations of retinol intake with bone mineral density (BMD) and bone maintenance in an ambulatory community-dwelling cohort of 570 women and 388 men, aged 55-92 years at baseline. Regression analyses, adjusted for standard osteoporosis covariates, showed an inverse U-shaped association of retinol, assessed by food-frequency questionnaires in 1988-1992, with baseline BMD, BMD measured 4 years later, and BMD change. Supplemental retinol use, reported by 50% of women and 39% of men, was an effect modifier in women; the associations of log retinol with BMD and BMD change were negative for supplement users and positive for nonusers at the hip, femoral neck, and spine. At the femoral neck, for every unit increase in log retinol intake, supplement users had 0.02 g/cm2 (p = 0.02) lower BMD and 0.23% (p = 0.05) greater annual bone loss, and nonusers had 0.02 g/cm2 (p = 0.04) greater BMD and 0.22% (p = 0.19) greater bone retention. However, among supplement users, retinol from dietary and supplement sources had similar associations with BMD, suggesting total intake is more important than source. In both sexes, increasing retinol became negatively associated with skeletal health at intakes not far beyond the recommended daily allowance (RDA), intakes reached predominately by supplement users. This study suggests there is a delicate balance between ensuring that the elderly consume sufficient vitamin A and simultaneously cautioning against excessive retinol supplementation.

Protein consumption and bone mineral density in the elderly : the Rancho Bernardo Study.

The role of dietary protein in osteoporosis is unclear, with previous studies having suggested both protection and harm. The associations of total, animal, and vegetable protein with bone mineral density (BMD) and the variations in these associations with calcium intake were studied in a community-dwelling cohort of 572 women and 388 men aged 55-92 years (Rancho Bernardo, California). Multiple linear regression analyses adjusted for standard osteoporosis covariates showed a positive association between animal protein consumption, assessed by food frequency questionnaires in 1988-1992, and BMD, measured 4 years later. This association was statistically significant in women. For every 15-g/day increase in animal protein intake, BMD increased by 0.016 g/cm2 at the hip (p = 0.005), 0.012 g/cm2 at the femoral neck (p = 0.02), 0.015 g/cm2 at the spine (p = 0.08), and 0.010 g/cm2 for the total body (p = 0.04). Conversely, a negative association between vegetable protein and BMD was observed in both sexes. Some suggestion of effect modification by calcium was seen in women, with increasing protein consumption appearing to be more beneficial for women with lower calcium intakes, but evidence for this interaction was not consistently strong. This study supports a protective role for dietary animal protein in the skeletal health of elderly women.