Evaluating causal associations of chronotype with pregnancy and perinatal outcomes and its interactions with insomnia and sleep duration: a mendelian randomization study.

Background: Observational studies suggested chronotype was associated with pregnancy and perinatal outcomes. Whether these associations are causal is unclear. Our aims are to use Mendelian randomization (MR) to explore (1) associations of evening preference with stillbirth, miscarriage, gestational diabetes, hypertensive disorders of pregnancy, perinatal depression, preterm birth and offspring birthweight; and (2) differences in associations of insomnia and sleep duration with those outcomes between chronotype preferences.

Telomere length in relation to fecundability and use of assisted reproductive technologies: the Norwegian Mother, Father, and Child Cohort Study.

Background: Telomere length (TL) has been reported to be associated with conditions such as endometriosis and polycystic ovary syndrome, with some studies finding associations with shorter TL and others with longer TL. In men, studies mostly report associations between shorter TL and sperm quality. To our knowledge, no studies have thus far investigated associations between TL and fecundability or the use of assisted reproductive technologies (ART).

Caesarean section and risk of infection in offspring: systematic review and meta-analysis of observational studies.

Objective: To compare the risk of hospital admissions with infections and infections not in hospital in children born by caesarean section with children born by vaginal birth.

Data Sources: Medline, Embase, and PubMed were searched with no restriction on start date up to 12 February 2024.

Study Selection: Observational studies were included that reported the association between caesarean section and vaginal birth in relation to the risk of infections (both those that lead to hospital admission and those that do not) up to 18 years of age.

Parental epigenetic age acceleration and risk of adverse birth outcomes: the Norwegian mother, father and child cohort study.

Background: Few studies have examined associations between maternal epigenetic age acceleration and adverse birth outcomes, and none have investigated paternal epigenetic age acceleration. Our objective was to assess the associations of parental (both maternal and paternal) epigenetic age acceleration in relation to birth outcomes.

Methods: Parental epigenetic age was estimated using seven established epigenetic clocks in 2198 mothers and 2193 fathers from the Norwegian Mother, Father, and Child Cohort Study (MoBa).

Environmental exposures and fecundability: The Norwegian Mother, Father, and Child Cohort study.

Previous studies have linked certain environmental exposures to reduced fecundability, influencing exposure recommendations. We continue to encounter numerous environmental exposures in our everyday lives, and further evidence is needed regarding their effects on fecundability. We evaluated associations between various self-reported environmental exposures and fecundability, measured as time to pregnancy, in 64,942 women and 53,219 men participating in the Norwegian Mother, Father, and Child Cohort study (MoBa).

Covid-19 vaccination and menstrual bleeding disturbances among women of fertile age: a Norwegian registry study.

This study evaluated the relationship between Covid-19 vaccination and menstrual bleeding disturbances using a large national registry linkage including 666,467 women between 20 and 40 years of age residing in Norway on January 1st, 2019. Information on vaccination-BNT162b2 and mRNA-1273 - was obtained from the Norwegian vaccination registry. Diagnoses of menstrual disturbances (absent/scanty, excessive, irregular/frequent menstruation, and intermenstrual bleeding) was obtained from the general practitioner database.

Daily snuff use during pregnancy, gestational length and birth weight; register-based study.

Background: Snuff is a smokeless source of nicotine that is common in Scandinavia and increasingly used by women of fertile age. Persistent use of snuff during pregnancy has been associated with adverse pregnancy outcomes. Emerging data from the Medical Birth Registry of Norway distinguishes between occasional use and daily use.

Sex differences in DNA methylation variations according to ART conception-evidence from the Norwegian mother, father, and child cohort study.

Previous studies have shown cord-blood DNA methylation differences in newborns conceived using assisted reproductive technologies (ART) compared to those conceived naturally. However, whether these ART-related DNA methylation differences vary with children's sex is unknown. We hypothesize that the DNA methylation differences in cord blood between ART-conceived and naturally conceived newborns also varies by the sex of the child, with distinct patterns of differential methylation present in males and females.

Covid-19 infection and vaccination during first trimester and risk of congenital anomalies: Nordic registry based study.

Objectives: To evaluate the risk of major congenital anomalies according to infection with or vaccination against covid-19 during the first trimester of pregnancy.

Design: Prospective Nordic registry based study.

Setting: Sweden, Denmark, and Norway.

Cardiovascular disease risk factors and infertility: multivariable analyses and one-sample Mendelian randomization analyses in the Trøndelag Health Study.

Study Question: Are cardiovascular disease (CVD) risk factors causally associated with higher risk of infertility among women and men?

Summary Answer: We found evidence to support a causal relationship between smoking initiation and history of infertility in women.

What Is Known Already: Several CVD risk factors are associated with history of infertility. Previous studies using Mendelian randomization (MR) further support a causal relationship between BMI and infertility in women.

Telomere length in relation to fecundability and use of assisted reproductive technologies: the Norwegian Mother, Father, and Child Cohort Study.

In women, shorter telomeres have been reported to be associated with conditions such as endometriosis and polycystic ovary syndrome, whereas other studies have reported the opposite. In men, studies mostly report associations between shorter telomeres and sperm quality. To our knowledge, no studies have thus far investigated the associations between TL and fecundability or the use of ART.

Assessing causal links between age at menarche and adolescent mental health: a Mendelian randomisation study.

Background: The timing of puberty may have an important impact on adolescent mental health. In particular, earlier age at menarche has been associated with elevated rates of depression in adolescents. Previous research suggests that this relationship may be causal, but replication and an investigation of whether this effect extends to other mental health domains is warranted.

Placental efflux transporters and antiseizure or antidepressant medication use impact birth weight in MoBa cohort.

Low birth weight raises neonatal risks and lifelong health issues and is linked to maternal medication use during pregnancy. We examined data from the Norwegian Mother, Father, and Child Cohort Study and the Medical Birth Registry of Norway, including 69,828 offspring with genotype data and 81,189 with maternal genotype data. We identified genetic risk variants in placental efflux transporters, calculated genetic scores based on alleles related to transporter activity, and assessed their interaction with prenatal use of antiseizure or antidepressant medication on offspring birth weight.

Neonatal Outcomes After COVID-19 Vaccination in Pregnancy.

Importance: Better knowledge about neonatal adverse events after COVID-19 vaccination during pregnancy could help address concerns about vaccine safety.

Objective: To evaluate the risks of neonatal adverse events after exposure to COVID-19 vaccination during pregnancy.

Design, Setting, And Participants: Population-based cohort study including all infants in Sweden and Norway born from June 2021 to January 2023.

Parental genetically predicted liability for coronary heart disease and risk of adverse pregnancy outcomes: a cohort study.

Background: Adverse pregnancy outcomes (APO) may unmask or exacerbate a woman's underlying risk for coronary heart disease (CHD). We estimated associations of maternal and paternal genetically predicted liability for CHD with lifelong risk of APOs. We hypothesized that associations would be found for women, but not their male partners (negative controls).

Parental infertility and offspring cardiometabolic trajectories: a pooled analysis of three European cohorts.

Objective: To assess whether parental infertility is associated with differences in cardiometabolic trajectories in offspring.

Design: Pooled observational analysis in three prospective cohorts.

Setting: Three nationwide pregnancy cohorts.

Comprehensive evaluation of smoking exposures and their interactions on DNA methylation.

Background: Smoking impacts DNA methylation, but data are lacking on smoking-related differential methylation by sex or dietary intake, recent smoking cessation (<1 year), persistence of differential methylation from in utero smoking exposure, and effects of environmental tobacco smoke (ETS).

Methods: We meta-analysed data from up to 15,014 adults across 5 cohorts with DNA methylation measured in blood using Illumina's EPIC array for current smoking (2560 exposed), quit < 1 year (500 exposed), in utero (286 exposed), and ETS exposure (676 exposed). We also evaluated the interaction of current smoking with sex or diet (fibre, folate, and vitamin C).

A Pregnancy and Childhood Epigenetics Consortium (PACE) meta-analysis highlights potential relationships between birth order and neonatal blood DNA methylation.

Higher birth order is associated with altered risk of many disease states. Changes in placentation and exposures to in utero growth factors with successive pregnancies may impact later life disease risk via persistent DNA methylation alterations. We investigated birth order with Illumina DNA methylation array data in each of 16 birth cohorts (8164 newborns) with European, African, and Latino ancestries from the Pregnancy and Childhood Epigenetics Consortium.