Women's prepregnancy lipid levels and number of children: a Norwegian prospective population-based cohort study

Follicular Fluid Proteomic Analysis of Women Undergoing Assisted Reproduction Suggests That Apolipoprotein A1 Is a Potential Fertility Marker

Infertility affects millions worldwide, posing a significant global health challenge. The proteomic analysis of follicular fluid provides a comprehensive view of the complex molecular landscape within ovarian follicles, offering valuable information on the factors influencing oocyte development and on the overall reproductive health. The follicular fluid is derived from the plasma and contains various proteins that can have different roles in oocyte health and infertility, and this fluid is a critical microenvironment for the developing oocytes as well. Using the high-performance liquid chromatography-mass spectrometry method, we investigated the protein composition of the follicular fluid, and after classification, we carried out relative quantification of the identified proteins in the pregnant (P) and non-pregnant (NP) groups. Based on the protein-protein interaction analysis, albumin and apolipoprotein A1 (ApoA1) were found to be hub proteins, and the quantitative comparison of the P and NP groups resulted in a significantly lower concentration of ApoA1 and high-density lipoprotein cholesterol in the P group. As both molecules are involved in the cholesterol transport, we also investigated their role in the development of oocytes and in the prediction of fertility.

Serum placental growth factor, total cholesterol, and triglycerides for prediction of intrahepatic cholestasis of pregnancy

This study aims to investigate the predictive values of serum placental growth factor (PIGF), total cholesterol (TC), and triglycerides (TG) in the context of intrahepatic cholestasis of pregnancy (ICP). This retrospective case control study recruited pregnant women from January 2021 to December 2021 at the Maternal and Child Health Hospital of Hunan Province, encompassing pregnant women diagnosed with ICP and those with unremarkable prenatal examinations. A total of 433 pregnant women were included, among whom 167 were diagnosed with ICP after 24 weeks of pregnancy. Patients with ICP exhibited an average age of 31.30 ± 4.54 years and an average pregnancy week at delivery of 37.63 ± 1.45 weeks. Multivariable regression analysis showed that the pregnancy week at delivery (OR = 0.823, 95% CI: 0.769-0.879, P < .001), PIGF (OR = 0.994, 95% CI: 0.992-0.996, P < .001), TC (OR = 1.955, 95% CI: 1.586-2.409, P < .001), and TG (OR = 3.786, 95% CI: 2.655-5.399, P < .001) were independent risk factors for ICP. The area under the curve values for PIGF, TC, and TG in predicting ICP were 0.858 (95% CI: 0.822-0.893), 0.721 (95% CI: 0.670-0.772), and 0.830 (95% CI: 0.788-0.871), respectively. However, their combination yielded an area under the curve value of 0.922 (95% CI: 0.898-0.946). The composite assessment of PIGF, TC, and TG demonstrates potential efficacy in predicting ICP among pregnant women.

The relationship between pregnancy count and duration of breast-feeding with metabolic syndrome (Fasa Persian cohort study)

BACKGROUND

Changes that occur during pregnancy and after that during breastfeeding induce some symptoms similar to metabolic syndrome (MetS) risk factors. This study aims to determine the relationship between pregnancy, as well as the duration of breastfeeding and MetS controlling the effect of other risk factors like hypertension, glucose intolerance, triglyceride, central obesity, and reduction of high-density lipoprotein in women of Fasa Persian Cohort Study.

MATERIALS AND METHODS

In this cross-sectional study, 5015 women aged 35-70 years were investigated in the Sheshdeh region from 2016 to 2021, and the information related to the disease symptoms was collected through questionnaires, examinations, and laboratory tests. MetS was calculated based on two guidelines according to adult treatment panel III (ATP III) and international diabetes federation (IDF) methods. For reporting the data, the odds ratio with its 95% confidence interval was used. In order to eliminate the effect of confounders, logistic regression was used.

RESULTS

Prevalence of MetS showed a descending trend in women with up to two pregnancies and it reached 22.6% and 22.4% using ATPIII and IDF methods respectively, while with an increase in the number of pregnancies of more than two, MetS prevalence was ascending. The prevalence of MetS did not have any specific trend across various breastfeeding duration groups. Multivariate analysis approved that the odds ratio of developing MetS in comparison with women who had two pregnancies was significantly increasing trend when the pregnancy counts increased.

CONCLUSION

The chance of developing MetS based on both IDF and ATP III methods after adjustment for confounding effects would grow with an increase in the number of pregnancies to more than two and breast-feeding of more than seven years. It is recommended that women with more than two pregnancies or the long duration of breast-feeding women undergo a specialized examination to investigate and control MetS problems so that future diseases could be prevented.

Long-term cardiovascular mortality in women with twin pregnancies by lifetime reproductive history

BACKGROUND

Women with one lifetime singleton pregnancy have increased risk of cardiovascular disease (CVD) mortality compared with women who continue reproduction particularly if the pregnancy had complications. Women with twins have higher risk of pregnancy complications, but CVD mortality risk in women with twin pregnancies has not been fully described.

OBJECTIVES

We estimated risk of long-term CVD mortality in women with naturally conceived twins compared to women with singleton pregnancies, accounting for lifetime number of pregnancies and pregnancy complications.

METHODS

Using linked data from the Medical Birth Registry of Norway and the Norwegian Cause of Death Registry, we identified 974,892 women with first pregnancy registered between 1967 and 2013, followed to 2020. Adjusted hazard ratios (aHR) with 95% confidence intervals (CI) for maternal CVD mortality were estimated by Cox regression for various reproductive history (exposure categories): (1) Only one twin pregnancy, (2) Only one singleton pregnancy, (3) Only two singleton pregnancies, (4) A first twin pregnancy and continued reproduction, (5) A first singleton pregnancy and twins in later reproduction and (6) Three singleton pregnancies (the referent group). Exposure categories were also stratified by pregnancy complications (pre-eclampsia, preterm delivery or perinatal loss).

RESULTS

Women with one lifetime pregnancy, twin or singleton, had increased risk of CVD mortality (adjusted hazard [HR] 1.72, 95% confidence interval [CI] 1.21, 2.43 and aHR 1.92, 95% CI 1.78, 2.07, respectively), compared with the referent of three singleton pregnancies. The hazard ratios for CVD mortality among women with one lifetime pregnancy with any complication were 2.36 (95% CI 1.49, 3.71) and 3.56 (95% CI 3.12, 4.06) for twins and singletons, respectively.

CONCLUSIONS

Women with only one pregnancy, twin or singleton, had increased long-term CVD mortality, however highest in women with singletons. In addition, twin mothers who continued reproduction had similar CVD mortality compared to women with three singleton pregnancies.

Exploring the associations between number of children, multi-partner fertility and risk of obesity at midlife: Findings from the 1970 British Cohort Study (BCS70)

BACKGROUND

Early parenthood, high parity, and partnership separation are associated with obesity. However, the emergence of non-marital partnerships, serial partnering and childbearing across unions, means that it is important to consider their association to obesity. This paper examined the associations between number of biological children and multi-partner fertility (MPF)-defined as having biological children with more than one partner, with obesity at midlife.

METHOD

The sample consisted of 2940 fathers and 3369 mothers in the 1970 British Cohort Study. The outcome was obesity (BMI 30 or over) at age 46. Fertility and partnership histories ascertained the number of live biological children and MPF status by age 42. The associations were tested using logistic regression adjusting for confounders at birth, age 10 and age 16. Adult factors recorded at age 42 including age at first birth, smoking status, alcohol dependency, educational attainment and housing tenure were considered as mediators.

RESULTS

For fathers, obesity odds did not differ according to number of children or MPF. In unadjusted models, mothers with one child (OR 1.24 95%CI 1.01-1.51), mothers who had two children with two partners (OR 1.45 95%CI 1.05-1.99), and mothers who had three or more children with two or more partners (OR 1.51 95%CI 1.18-1.93) had higher odds of obesity. In adjusted models, there remained an association between mothers with one child and odds of obesity (OR 1.30 95%CI 1.05-1.60). All other associations were attenuated when confounders were included.

CONCLUSIONS

Mothers who had children with multiple partners had higher odds of obesity. However this association was completely attenuated when parental and child confounders were accounted for; suggesting that this association may be explained by confounding. Mothers who had one child only may be at increased odds of obesity, however this could be due to multiple factors including age at first birth.

Implications of High-Density Cholesterol Metabolism for Oocyte Biology and Female Fertility

Cholesterol is an essential component of animal cells. Different regulatory mechanisms converge to maintain adequate levels of this lipid because both its deficiency and excess are unfavorable. Low cell cholesterol content promotes its synthesis and uptake from circulating lipoproteins. In contrast, its excess induces the efflux to high-density lipoproteins (HDL) and their transport to the liver for excretion, a process known as reverse cholesterol transport. Different studies suggest that an abnormal HDL metabolism hinders female fertility. HDL are the only lipoproteins detected in substantial amounts in follicular fluid (FF), and their size and composition correlate with embryo quality. Oocytes obtain cholesterol from cumulus cells via gap junctions because they cannot synthesize cholesterol de novo and lack HDL receptors. Recent evidence has supported the possibility that FF HDL play a major role in taking up excess unesterified cholesterol (UC) from the oocyte. Indeed, genetically modified mouse models with disruptions in reverse cholesterol transport, some of which show excessive circulating UC levels, exhibit female infertility. Cholesterol accumulation can affect the egg´s viability, as reported in other cell types, and activate the plasma membrane structure and activity of membrane proteins. Indeed, in mice deficient for the HDL receptor Scavenger Class B Type I (SR-B1), excess circulating HDL cholesterol and UC accumulation in oocytes impairs meiosis arrest and hinders the developmental capacity of the egg. In other cells, the addition of cholesterol activates calcium channels and dysregulates cell death/survival signaling pathways, suggesting that these mechanisms may link altered HDL cholesterol metabolism and infertility. Although cholesterol, and lipids in general, are usually not evaluated in infertile patients, one study reported high circulating UC levels in women showing longer time to pregnancy as an outcome of fertility. Based on the evidence described above, we propose the existence of a well-regulated and largely unexplored system of cholesterol homeostasis controlling traffic between FF HDL and oocytes, with significant implications for female fertility.

Lipid levels after childbirth and association with number of children: A population-based cohort study

OBJECTIVE

Low parity women are at increased risk of cardiovascular mortality. Unfavourable lipid profiles have been found in one-child mothers years before they conceive. However, it remains unclear whether unfavourable lipid profiles are evident in these women also after their first birth. The aim was to estimate post-pregnancy lipid levels in one-child mothers compared to mothers with two or more children and to assess these lipid's associations with number of children.

METHODS

We used data on 32 618 parous women (4 490 one-child mothers and 28 128 women with ≥2 children) examined after first childbirth as part of Cohort of Norway (1994-2003) with linked data on reproduction and number of children from the Medical Birth Registry of Norway (1967-2008). Odds ratios (ORs) with 95% confidence intervals (CIs) for one lifetime pregnancy (vs. ≥2 pregnancies) by lipid quintiles were obtained by logistic regression and adjusted for age at examination, year of first birth, body mass index, oral contraceptive use, smoking and educational level.

RESULTS

Compared to women with the lowest quintiles, ORs for one lifetime pregnancy for the highest quintiles of LDL and total cholesterol were 1.30 (95%CI: 1.14-1.45) and 1.43 (95%CI: 1.27-1.61), respectively. Sensitivity analysis (women <40 years) showed no appreciable change in our results. In stratified analyses, estimates were slightly stronger in overweight/obese, physically inactive and women with self-perceived bad health.

CONCLUSIONS

Mean lipid levels measured after childbirth in women with one child were significantly higher compared to mothers with two or more children and were associated with higher probability of having only one child. These findings corroborate an association between serum lipid levels and one lifetime pregnancy (as a feature of subfecundity), emphasizing that these particular women may be a specific predetermined risk group for cardiovascular related disease and death.

[Reproductive Toxicological Research as Countermeasures to Declining Birth Rate]

Research into reproductive toxicology may lead to one of the countermeasures to the declining birth rate observed in industrialized countries. Some chemicals can pose risks to human reproduction that is a multistage process starting from the development of male and female germ cells to childbirth and the subsequent growth and development of the child. In Japan, the government has amended law enforcement, i.e., the Regulations on Labor Standards for Women, recently to improve protection for pregnant women against reproductive chemical hazards in workplaces. Male workers may also be protected against such hazards if appropriate risk assessment and the following management are performed as required by the Industrial Safety and Health Law. However, it remains a concern that an unexpected adverse outcome due to an unknown reproduction hazard may occur owing to the use of chemicals not listed in the regulations. This is because the toxicity of a large number of chemicals has not been entirely revealed. Moreover, it is often difficult to determine from a Safety Data Sheet for a product of interest whether the chemicals contained in the product do not have reproductive toxicity or the toxicity data are just not available because of lack of pertinent studies. Thus, researchers in the field of occupational and environmental health need to make effort to fill in such data gaps and to raise the awareness among the public the importance of experimental and epidemiological studies. Study designs for investigating subclinical effects, mechanisms of reproductive toxicity, exposure levels, and dose-response relationships to determine environmental standards are also required.