In this cohort of 120 postpartum women with major depression, plasma lipids were observed to be elevated between 1 and 14 weeks postpartum. The very high early postpartum total cholesterol and LDL-C levels we found in postpartum women with depression are consistent with results in the sparse literature published more than three decades ago on general populations of postpartum women. In 1979, Potter and Nestel5
reported that plasma lipids were elevated postpartum. They followed 43 women through pregnancy and the first year after delivery and found total cholesterol elevated at an average just above 250
mg/dL at 6 weeks and still slightly higher than prepregnancy baseline at 52 weeks. Darmody and Postle17
studied 34 women and showed a similar pattern and values for total cholesterol at approximately 250
mg/dL at 6 weeks, but they reported a return to baseline by 40 weeks.
Van Stiphout et al.6
compared total cholesterol and HDL-C in 831 Dutch women and reported that women who had ever been pregnant had slightly higher total cholesterol and lower HDL-C levels than similar never pregnant women. Sixty women studied from early pregnancy through 40 days postpartum by Jimenez et al.1
showed persistently elevated total cholesterol at 40 days, with a mean of 240
mg/day. As in our study, women who breastfed had more favorable lipid profiles postpartum than had their formula-feeding peers.17,18
Physiologically, this is plausible, based on alterations in lipid metabolism required for lactation. It is also possible that breastfeeding is a marker for overall better health, as women who breastfeed tend to be healthier, with higher socioeconomic status and educational attainment, than formula-feeding women. The potential positive effect of breastfeeding on lipids could represent a reduction in long-term risk and is an additional reason to promote breastfeeding to improve public health.
Both older age and higher BMI have been shown to be associated with elevated total cholesterol and LDL-C, as in our study.19
Although African Americans have higher rates of CVD, race has not been consistently shown to be associated with differences in lipid profiles.20
Previous studies of postpartum lipids have shown no association with maternal age1,5,17,18,21
Several studies, however, either did not examine these covariants, did not report their significance, or only examined them in relation to change in lipids over time rather than for absolute lipid levels. Because of this, as well as the multiethnic nature of our sample and the increasing rate of obesity in the United States since some of the older studies were published, it is difficult to accurately compare these results.
HDL-C has been studied more recently. In two published reports from the Coronary Artery Risk Development in Young Adults (CARDIA) study,21,22
postpartum HDL-C was found to be decreased compared to prepregnancy levels for a period of 10 years after the first pregnancy, consistent with van Stiphout's findings.6
This is suggestive of long-term lipid alterations produced by pregnancy.
The strengths of this study include the relatively large sample of postpartum women who provided standardized, fasting measures of plasma lipids done in the same laboratory. Laboratory assessments for thyroid function, complete blood count (CBC), full metabolic screens, and detailed information on breastfeeding status were available for all participants. The data () provide a visual representation of the decline in total cholesterol by postpartum week to aid interpretation of laboratory values obtained in postpartum women. We established the average time of return of cholesterol to the desired value of <200
mg/dL to be 6 weeks after birth. Study participants were recruited from a diverse community, which increases generalizability. Finally, PPD was diagnosed objectively with DSM-4 diagnostic interviews.
Although the sample size allows a reasonable evaluation of postpartum lipids, it is too small to identify contributions from pregnancy complications, such as preeclampsia or gestational diabetes. Likewise, it would be preferable to have prepregnancy BMI on all subjects, and some are missing from this sample. Because of methodologic differences, we are unable to directly compare the results from our depressed population with the populations previously studied. Finally, prepregnancy lipid levels for comparison would allow us to make interperson comparisons that we are unable to do with our current data.
The possible long-term effects of elevated postpartum lipids on health, including potential interaction with depression as well as cardiovascular health, are an area for further study. In depressed patients, lipoprotein structure is changed toward increasing LDL-C and higher atherogenic potential, and remission is associated with improvement of the LDL-C/HDL-C ratio.23
Longitudinal assessment to determine if subgroups of postpartum women at risk (such as those with depression) have sustained serum cholesterol elevations are also needed. The women in this RCT will be evaluated for lipid profiles related to both treatment assignment and remission status at study completion. People with severe mental illness, including refractory depression, are at increased risk of early death.24
Women with depression are more likely to be obese and may already be at increased risk of death from CVD. Additional studies on the effects of reproductive life, including pregnancy and lactation, are required to understand the cumulative burden of risk factors throughout life and their role in future health. This study is the first step in understanding whether physiologic changes in lipid metabolism caused by pregnancy may affect long-term health outcomes in women with depression.