Maternal Smoking Among Women With and Without Use of Assisted Reproductive Technologies

Intergenerational transmission of tobacco smoking: The role of the child's behavioral difficulties. Data from the Danish National Birth cohort (DNBC)

AIMS

This study explores the role of offspring behavioral difficulties in the intergeneration transmission of tobacco smoking.

METHODS

This longitudinal cohort study is based on children born in Denmark in 1996-2003 participating in the Danish National Birth Cohort (DNBC), followed-up until 18years of age. We included mother-child pairs with complete data regarding the exposure (4 trajectories of maternal daily smoking quantity during pregnancy: low, intermediate/stable, intermediate/decreasing and high), outcome (offspring daily smoking status at 18 years) and mediator (offspring symptoms of hyperactivity-inattention at 11 years), that is 24,588 mother-child pairs.

RESULTS

In our study population, during pregnancy respectively 86.2%, 6.80%, 4.08% and 2.97% mothers belonged to the low, intermediate/stable, intermediate/decreasing and high smoking trajectory groups. After controlling for covariates using propensity scores, the direct effect of maternal smoking in pregnancy on offspring smoking in adolescence was statistically significant, especially when the mother belonged to the intermediate/stable smoking trajectory group (ORIPW = 2.09, 95% CI: 1.70 - 2.61) or to the high smoking trajectory group (ORIPW = 2.08, 95% CI: 1.52 - 3.11) compared to the low smoking trajectory group. None of the indirect effects of maternal smoking in pregnancy were statistically significant, and neither were the proportions mediated.

CONCLUSION

Maternal pregnancy smoking seems to have an influence on offspring smoking in early adulthood, which does not appear to be mediated by offspring behavioral difficulties. Women should be strongly encouraged to quit smoking in pregnancy to reduce both short and long-term health risks among their offspring.

The X-factor in ART: does the use of assisted reproductive technologies influence DNA methylation on the X chromosome?

BACKGROUND

Assisted reproductive technologies (ART) may perturb DNA methylation (DNAm) in early embryonic development. Although a handful of epigenome-wide association studies of ART have been published, none have investigated CpGs on the X chromosome. To bridge this knowledge gap, we leveraged one of the largest collections of mother-father-newborn trios of ART and non-ART (natural) conceptions to date to investigate sex-specific DNAm differences on the X chromosome. The discovery cohort consisted of 982 ART and 963 non-ART trios from the Norwegian Mother, Father, and Child Cohort Study (MoBa). To verify our results from the MoBa cohort, we used an external cohort of 149 ART and 58 non-ART neonates from the Australian 'Clinical review of the Health of adults conceived following Assisted Reproductive Technologies' (CHART) study. The Illumina EPIC array was used to measure DNAm in both datasets. In the MoBa cohort, we performed a set of X-chromosome-wide association studies ('XWASs' hereafter) to search for sex-specific DNAm differences between ART and non-ART newborns. We tested several models to investigate the influence of various confounders, including parental DNAm. We also searched for differentially methylated regions (DMRs) and regions of co-methylation flanking the most significant CpGs. Additionally, we ran an analogous model to our main model on the external CHART dataset.

RESULTS

In the MoBa cohort, we found more differentially methylated CpGs and DMRs in girls than boys. Most of the associations persisted after controlling for parental DNAm and other confounders. Many of the significant CpGs and DMRs were in gene-promoter regions, and several of the genes linked to these CpGs are expressed in tissues relevant for both ART and sex (testis, placenta, and fallopian tube). We found no support for parental DNAm-dependent features as an explanation for the observed associations in the newborns. The most significant CpG in the boys-only analysis was in UBE2DNL, which is expressed in testes but with unknown function. The most significant CpGs in the girls-only analysis were in EIF2S3 and AMOT. These three loci also displayed differential DNAm in the CHART cohort.

CONCLUSIONS

Genes that co-localized with the significant CpGs and DMRs associated with ART are implicated in several key biological processes (e.g., neurodevelopment) and disorders (e.g., intellectual disability and autism). These connections are particularly compelling in light of previous findings indicating that neurodevelopmental outcomes differ in ART-conceived children compared to those naturally conceived.

Effect of paternal smoking on pre-implantation embryonic development: a prospective cohort study

CONTEXT

Recent studies have failed to demonstrate the negative impact of male tobacco smoking on embryo development, raising the question of its actual implication on natural fecundity and assisted reproductive techniques outcomes.

AIMS

To assess the impact of paternal smoking on embryo development.

METHODS

In this prospective cohort study, 252 men from couples undergoing in vitro fertilisation (IVF) were included. Each patient was interviewed and took a carbon monoxide breath-test, creating three groups: non-smokers (n=113), former smokers (n=81) and active smokers (n=58). The Top-grade embryo ratio (primary endpoint), embryo morphokinetic parameters and clinical outcomes were assessed.

KEY RESULTS

In a multivariate analyses based on 1521 embryos, no significant difference was found in the top-grade embryo ratio between the groups. Tobacco smoking had no impact on clinical outcomes. Compared to non-smokers the time to the pronuclei fading (tPNf, P=0.006) and the time to the first embryonic cleavage (t2, P=0.002) were shorter in smokers, and the t2 was also slightly shorter in former smokers (P=0.045). No other differences were found in the morphokinetic parameters.

CONCLUSION

Even if a few differences were observed in the first timing of embryonic events, this study did not highlight a major embryonic and clinical impact of the paternal smoking status.

IMPLICATION

The results obtained here are reassuring towards IVF outcomes. As maternal smoking is highly controlled in the IVF patients in this study, we speculate that the sperm selection process may limit the adverse effects of tobacco consumption on embryo development.

Nomograms for predicting adverse obstetric outcome in IVF pregnancy: A preliminary study

BACKGROUND

In a previous study, we showed that the obstetric complication rate after in vitro fertilization (IVF) pregnancy was 40%. The main objective of our study was to determine maternal prognosis factors that influence the IVF pregnancy outcome.

METHODS

We conducted an observational retrospective monocentric study between January 2014 and January 2018. Pregnancy over 22 gestational weeks (GW) obtained after IVF in our infertility clinic was included. Maternal characteristics and pregnancy outcome were collected.

RESULTS

Data from 498 IVF pregnancies were analyzed. The most significant maternal prognosis factors for obstetric complications were maternal age above 40 years (OR 3,0 [95% IC 1,30-7,09], P = 0,010), twin pregnancies (3.8 [95% IC 1.49-9.99], P = .005), daily maternal smoking above 10 cigarettes (7.1 [95% IC 1.22-41.74], P = .029), maternal obesity (2.2 [95% IC 1.19-4.07], P = .012), endometriosis stages III and IV (6.4 [95% IC 1.52-27.04], P = .011), and history of ovarian hyperstimulation syndrome (OHSS) in early pregnancy (5.7 [95% IC 1.29-24.74], P = .021). Risk increase was independent of pregnancy type (singleton or twin) and allowed the elaboration of 2 nomograms.

CONCLUSIONS

Our study showed a link between some maternal factors and increase in obstetric complications after IVF. Screening of these factors during preconceptional visit is essential to identify at high-risk pregnancies and adapt their monitoring.

Trichostatin A alleviated ovarian tissue damage caused by cigarette smoke exposure

Cigarette smoke (CS) has a negative impact on women's health and fertility. Studies have shown that histone deacetylases 1 and 2 (HDAC1/2) were involved in oocyte development. However, the roles of HDAC1/2 in ovarian toxicity caused by CS exposure and the therapeutic potential of trichostatin A (TSA, a HDAC inhibitor) for ovarian tissue damage have not been investigated. In this study, Female C57BL/6 mice were exposed to CS from six cigarettes mixed with indoor air for 120 min (one cigarette for 20 min) using a whole-body mainstream smoke exposure system twice daily for 30 days. TSA (0.6 mg/kg body weight) was injected intraperitoneally into mice in the Control + TSA group and CS + TSA group every two days for 30 days. We found that exposure to CS resulted in ovarian tissue damage and HDAC1/2 over-expression. TSA alleviated the structural changes of ovarian tissue induced by smoking and prevented the activation of HDAC1/2. Exposure to CS caused autophagy inhibition and pyroptosis activation. TSA treatment restored the expression of autophagy-associated proteins and decreased the levels of pyroptosis-related proteins induced by CS exposure. The TSA effect may be mediated by inhibition of HDAC1/2 involved in autophagy and pyroptosis process.

Smoking and Clinical Outcomes of Assisted Reproductive Technologies

BACKGROUND

Smoking near conception has adverse effects on pregnancy outcomes. We estimated the proportion of assisted reproductive technology (ART) cycles with smoking reported and associated clinical outcomes.

METHODS

We used a retrospective cohort study (2009-2013) using national data of ART cycles in the United States. We compared patient characteristics, infertility diagnoses, and treatment procedures by self-reported smoking in the 3 months before treatment. Using multivariable logistic regression accounting for clustering by state, clinic, and patient, we assessed adjusted odds ratios (aOR) and 95% confidence intervals (CI) between smoking and clinical outcomes: cycle cancellations among all cycles (cycle stopped before retrieval of eggs or transfer of embryos), treatment outcomes (implantation, ectopic pregnancy, intrauterine pregnancy, and live birth) among cycles with ≥1 fresh embryo transferred, and pregnancy outcomes (miscarriage, stillbirth, and live birth) among intrauterine pregnancies.

RESULTS

Smoking was reported in 1.9% of cycles. Higher proportions of cycles among smokers versus nonsmokers were younger, non-Hispanic White, multigravida women and had tubal factor and male factor infertility diagnoses; lower proportions had diagnoses of diminished ovarian reserve and unexplained infertility, and used donor eggs. Smoking was associated with higher adjusted odds of cycle cancellation with no embryo transfer (aOR: 1.10; 95% CI: 1.00-1.21) and cancellations before fresh oocyte retrieval or frozen embryo transfer (1.11; 1.02-1.21). Associations between other clinical outcomes were nonsignificant.

CONCLUSIONS

Over 12,000 ART cycles in the United States were exposed to smoking during 2009-2013; smoking increased the odds of cycle cancellation. Providers should encourage women to quit smoking before ART treatments.

Knowledge regarding factors that influence fertility in Thai reproductive-age population living in urban area: A cross-sectional study

Objective

To survey knowledge about the factors that influence fertility in a reproductive-age population living in an urban area.

Methods

A cross-sectional study was conducted using a questionnaire-based survey among both males and females aged 18–45 years living in the Bangkok metropolitan area.

Results

The mean age of the participants was 26.8±7.2 years (male, 41.9%; female, 58.1%). Of the participants, 53.1% had an undergraduate degree and 57.1% were single. Only one-fifth of the participants correctly identified the age when fecundity declines in male and female, the definition of infertility, and the period during the menstrual cycle with the highest chance of pregnancy. Approximately three-fourths of the participants correctly identified that cigarette smoking, alcohol consumption, and sexually transmitted infections affect fertility.

Conclusion

A considerable knowledge gap about the factors that influence fertility was identified in reproductive-age individuals in an urban area of Thailand. This issue should be urgently addressed by promoting fertility awareness through education, discussions about social perceptions regarding fertility, and reliable sources of knowledge.

Education in Twins and Their Parents Across Birth Cohorts Over 100 years: An Individual-Level Pooled Analysis of 42-Twin Cohorts

Whether monozygotic (MZ) and dizygotic (DZ) twins differ from each other in a variety of phenotypes is important for genetic twin modeling and for inferences made from twin studies in general. We analyzed whether there were differences in individual, maternal and paternal education between MZ and DZ twins in a large pooled dataset. Information was gathered on individual education for 218,362 adult twins from 27 twin cohorts (53% females; 39% MZ twins), and on maternal and paternal education for 147,315 and 143,056 twins respectively, from 28 twin cohorts (52% females; 38% MZ twins). Together, we had information on individual or parental education from 42 twin cohorts representing 19 countries. The original education classifications were transformed to education years and analyzed using linear regression models. Overall, MZ males had 0.26 (95% CI [0.21, 0.31]) years and MZ females 0.17 (95% CI [0.12, 0.21]) years longer education than DZ twins. The zygosity difference became smaller in more recent birth cohorts for both males and females. Parental education was somewhat longer for fathers of DZ twins in cohorts born in 1990-1999 (0.16 years, 95% CI [0.08, 0.25]) and 2000 or later (0.11 years, 95% CI [0.00, 0.22]), compared with fathers of MZ twins. The results show that the years of both individual and parental education are largely similar in MZ and DZ twins. We suggest that the socio-economic differences between MZ and DZ twins are so small that inferences based upon genetic modeling of twin data are not affected.