Pregnancy and risk of COVID-19: a Norwegian registry-linkage study

Objective

To compare the risk of acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection and contact with specialist healthcare services for coronavirus disease 2019 (COVID‐19) between pregnant and non‐pregnant women.

Population or sample

All women ages 15–45 living in Norway on 1 March 2020 (n = 1 033 699).

Methods

We linked information from the national birth, patient, communicable diseases and education databases using unique national identifiers.

Main outcome measure

We estimated hazard ratios (HR) among pregnant compared to non‐pregnant women of having a positive test for SARS‐CoV‐2, a diagnosis of COVID‐19 in specialist healthcare, or hospitalisation with COVID‐19 using Cox regression. Multivariable analyses adjusted for age, marital status, education, income, country of birth and underlying medical conditions.

Results

Pregnant women were not more likely to be tested for or to a have a positive SARS‐CoV‐2 test (adjusted HR 0.99; 95% CI 0.92–1.07). Pregnant women had higher risk of hospitalisation with COVID‐19 (HR 4.70, 95% CI 3.51–6.30) and any type of specialist care for COVID‐19 (HR 3.46, 95% CI 2.89–4.14). Pregnant women born outside Scandinavia were less likely to be tested, and at higher risk of a positive test (HR 2.37, 95% CI 2.51–8.87). Compared with pregnant Scandinavian‐born women, pregnant women with minority background had a higher risk of hospitalisation with COVID‐19 (HR 4.72, 95% CI 2.51–8.87).

Conclusion

Pregnant women were not more likely to be infected with SARS‐CoV‐2. Still, pregnant women with COVID‐19, especially those born outside of Scandinavia, were more likely to be hospitalised.

Tweetable abstract

Pregnant women are at increased risk of hospitalisation for COVID‐19.

Pregnant women are at increased risk of hospitalisation for COVID‐19.

Clinical characteristics including cardiovascular and metabolic risk factors in adolescents with psoriasis

BACKGROUND

Clinical studies on psoriasis in adolescents have mainly been performed in patients with severe psoriasis. Population-based studies of clinical characteristics and risk factors for later cardiovascular and metabolic disease in children and adolescents are lacking.

OBJECTIVES

To examine the clinical characteristics of adolescents with psoriasis nested in a general population cohort. Furthermore, to investigate cardiovascular and metabolic risk factors in the adolescents with psoriasis compared to parentally predisposed and non-predisposed adolescents without psoriasis from the same birth cohort.

METHODS

We identified adolescents with and without psoriasis using a nationwide general population birth cohort in Denmark. A clinical examination included skin inspection and scoring of psoriasis severity, completion of a questionnaire on psoriasis and comorbidities, physical measurements, and blood sampling. Participants also completed self-administered questionnaires on quality of life and mental health.

RESULTS

We included 81 adolescents with psoriasis and 234 controls (110 with genetic predisposition for psoriasis and 124 without predisposition). Median age was 15.6 (13.5-18.5) years, and in those with active psoriasis, median Psoriasis Area and Severity Index score was 1.2 (0.1-11.4). The scalp was the most common site of psoriasis, both at debut and at time of examination. Diaper rash in infancy was more frequent in the psoriasis group. No significant differences regarding quality of life, anxiety and depression were found. More adolescents with psoriasis were obese (8.6% vs. 1.7%, P = 0.008), and physical measures of abdominal obesity were also significantly higher. HbA1c was significantly higher (31.55 vs. 30.81 mmol/mol, P = 0.048), while no differences were found for blood pressure, lipids or high-sensitivity C-reactive protein. In a subgroup analysis, this was evident in the non-predisposed psoriasis-free controls only.

CONCLUSIONS

Overall, adolescents with psoriasis from this general population had mild disease. Still, early markers of cardiovascular and metabolic disease were elevated.

Oral contraceptive use and genital anomalies in sons. A Danish cohort study

Exposure to exogenous sex hormones with estrogenic or anti-androgen properties may influence intrauterine development of male genitals. This population-based cohort study based on data from 44,408 live-born singleton sons in the Danish National Birth Cohort (DNBC) aimed to investigate whether maternal use of oral contraceptives prior to or during early pregnancy increase the risk of cryptorchidism or hypospadias. We found no consistent association between use of oral contraceptives and cryptorchidism or hypospadias, neither in those exposed any time four months prior to conception [cryptorchidism: adjusted Odds Ratio (aOR): 1.06 (95% CI: 0.91; 1.23), hypospadias: 0.74 (95% CI: 0.53; 1.03)] nor in those exposed any time during the first trimester of pregnancy [cryptorchidism: aOR: 0.93 (95% CI: 0.53; 1.62), hypospadias: 1.02 (95% CI: 0.32; 3.23)]. Despite relatively strong exposure levels from oral contraceptive use in pregnancy, this study revealed no evidence of an increased risk of either two genital malformations.

Impact of maternal body mass index and gestational weight gain on pregnancy complications: an individual participant data meta-analysis of European, North American and Australian cohorts

OBJECTIVE

To assess the separate and combined associations of maternal pre-pregnancy body mass index (BMI) and gestational weight gain with the risks of pregnancy complications and their population impact.

DESIGN

Individual participant data meta-analysis of 39 cohorts.

SETTING

Europe, North America, and Oceania.

POPULATION

265 270 births.

METHODS

Information on maternal pre-pregnancy BMI, gestational weight gain, and pregnancy complications was obtained. Multilevel binary logistic regression models were used.

MAIN OUTCOME MEASURES

Gestational hypertension, pre-eclampsia, gestational diabetes, preterm birth, small and large for gestational age at birth.

RESULTS

Higher maternal pre-pregnancy BMI and gestational weight gain were, across their full ranges, associated with higher risks of gestational hypertensive disorders, gestational diabetes, and large for gestational age at birth. Preterm birth risk was higher at lower and higher BMI and weight gain. Compared with normal weight mothers with medium gestational weight gain, obese mothers with high gestational weight gain had the highest risk of any pregnancy complication (odds ratio 2.51, 95% CI 2.31- 2.74). We estimated that 23.9% of any pregnancy complication was attributable to maternal overweight/obesity and 31.6% of large for gestational age infants was attributable to excessive gestational weight gain.

CONCLUSIONS

Maternal pre-pregnancy BMI and gestational weight gain are, across their full ranges, associated with risks of pregnancy complications. Obese mothers with high gestational weight gain are at the highest risk of pregnancy complications. Promoting a healthy pre-pregnancy BMI and gestational weight gain may reduce the burden of pregnancy complications and ultimately the risk of maternal and neonatal morbidity.

TWEETABLE ABSTRACT

Promoting a healthy body mass index and gestational weight gain might reduce the population burden of pregnancy complications.

Fever and infections during pregnancy and psychosis-like experiences in the offspring at age 11. A prospective study within the Danish National Birth Cohort

BACKGROUND

Maternal exposures to fever and infections in pregnancy have been linked to subsequent psychiatric morbidity in the child. This study examined whether fever and common infections in pregnancy were associated with psychosis-like experiences (PLEs) in the child.

METHODS

A longitudinal study of 46 184 children who participated in the 11-year follow-up of the Danish National Birth Cohort was conducted. Pregnant women were enrolled between 1996 and 2002 and information on fever, genitourinary infections, respiratory tract infection, and influenza-like illness during pregnancy was prospectively collected in two interviews during pregnancy. PLEs were assessed using the seven-item Adolescent Psychotic-Like Symptom Screener in a web-based questionnaire completed by the children themselves at age 11.

RESULTS

PLEs were reported among 11% of the children. Multinomial logistic regression models with probability weights to adjust for potential selection bias due to attrition suggested that maternal fever, genitourinary infections and influenza-like illness were associated with a weak to moderate increased risk of subclinical psychosis-like symptoms in the offspring, whereas respiratory tract infections were not. No clear pattern was observed between the strengths of the associations and the timing of exposure, or the type of psychosis-like symptom.

CONCLUSIONS

In this study, maternal exposures to fevers and common infections in pregnancy were generally associated with a subtle excess risk of PLEs in the child. A more pronounced association was found for influenza-like illness under an a priori definition, leaving open the possibility that certain kinds of infections may constitute important risk factors.

Fever in pregnancy and the risk of congenital malformations: a cohort study

Background

In a variety of animal species, hyperthermia in pregnancy has been recognized as teratogenic. Hyperthermia interferes with protein synthesis via heat-shock proteins, which can entail membrane disruption, cell death, vascular disruption, and placental infarction. This can induce severe fetal malformations or death. Fever during pregnancy, especially during embryogenesis, has also been associated with congenital malformations in human offspring.

The purpose of this large cohort study of clinically recognized pregnancies was to investigate whether fever during first trimester was associated with an increased risk of congenital malformations in the offspring.

Methods

The Danish National Birth Cohort is a population-based cohort of 100,418 pregnant women and their offspring recruited in 1996 to 2002. Information on fever during pregnancy was collected prospectively by means of two telephone interviews.

The study population comprised the 77,344 pregnancies enrolled in the Danish National Birth Cohort where self-reported information on fever during first trimester of pregnancy was available. Pregnancy outcomes were identified through linkage with the National Patient Registry. Congenital malformations within the first three and a half years of life were categorized according to EUROCAT’s classification criteria. Logistic regression models were used to estimate the associations between fever in first trimester and overall congenital malformations and congenital malformations by subgroups.

Results

Eight thousand three hundred twenty-one women reported fever during first trimester (10.8%) and 2876 infants were diagnosed with a congenital malformation (3.7%). Fever during first trimester did not affect the risk of overall fetal congenital malformation (OR 0.99, 95% CI 0.88–1.12). The subgroup analyses indicated slightly higher risk of congenital anomalies in the eye, ear, face and neck (OR 1.29, 95% CI 0.78–2.12) and in the genitals (OR 1.17, 95% CI 0.79–1.12), whereas lower risk of malformations in the nervous system (OR 0.47, 95% CI 0.21–1.08), the respiratory system (OR 0.56, 95% CI 0.23–1.29) and in the urinary subgroup (OR 0.58, 95% CI 0.35–0.99) was suggested, the latter constituting the only statistically significant finding.

Conclusions

Overall, this study did not show any association between maternal fever in pregnancy and risk of congenital anomalies.

Childhood psychopathology in children of women with eating disorders

OBJECTIVE

We aimed to investigate the effect of maternal eating disorders (ED) on childhood psychopathology, early delays in cognitive, motor and language development, mother and child relationship, and child temperament in a community-based cohort: the Danish National Birth Cohort (DNBC).

METHOD

Data were obtained prospectively on 48 403 children at 18 months and 46 156 children at 7 years. Data on cognitive, motor and language development, temperament and attachment were obtained at 18 months; data on child psychopathology were obtained at 7 years of age, using the Strengths and Difficulties Questionnaire (SDQ). Children of mothers with lifetime diagnosis of anorexia nervosa (AN, n = 931), lifetime diagnosis of bulimia nervosa (BN, n = 906) and both (AN & BN = 360) were compared to children of mothers without an ED (n = 46 206).

RESULTS

Girls of women with lifetime AN had higher odds of having emotional problems, and girls of women with lifetime BN of having conduct problems compared with children of healthy women. Boys of women with lifetime AN had higher odds of total, emotional and conduct problems; boys of women with lifetime BN had higher odds of total, conduct, hyperactivity and peer difficulties compared to children of women without an ED. Boys of women with lifetime AN and BN had higher odds of total, emotional and peer problems compared to children of healthy women.

CONCLUSION

Maternal ED is associated with childhood psychopathology in both boys and girls. Boys seemed at higher risk for psychopathology in this sample. Associations between emotional disorders across genders in children of mothers with lifetime AN, and hyperactivity and peer difficulties in boys of mothers with lifetime BN confirm and extend previous findings and point to possible shared risk between ED and other psychopathology.

Risk of congenital anomalies after exposure to asthma medication in the first trimester of pregnancy - a cohort linkage study

Objective

To examine the effect of maternal exposure to asthma medications on the risk of congenital anomalies.

Design

Meta‐analysis of aggregated data from three cohort studies.

Setting

Linkage between healthcare databases and EUROCAT congenital anomaly registries.

Population

519 242 pregnancies in Norway (2004–2010), Wales (2000–2010) and Funen, Denmark (2000–2010).

Methods

Exposure defined as having at least one prescription for asthma medications issued (Wales) or dispensed (Norway, Denmark) from 91 days before to 91 days after the pregnancy start date. Odds ratios (ORs) were estimated separately for each register and combined in meta‐analyses.

Main outcome measures

ORs for all congenital anomalies and specific congenital anomalies.

Results

Overall exposure prevalence was 3.76%. For exposure to asthma medication in general, the adjusted OR (adjOR) for a major congenital anomaly was 1.21 (99% CI 1.09–1.34) after adjustment for maternal age and socioeconomic position. The OR of anal atresia was significantly increased in pregnancies exposed to inhaled corticosteroids (3.40; 99% CI 1.15–10.04). For severe congenital heart defects, an increased OR (1.97; 1.12–3.49) was associated with exposure to combination treatment with inhaled corticosteroids and long‐acting beta‐2‐agonists. Associations with renal dysplasia were driven by exposure to short‐acting beta‐2‐agonists (2.37; 1.20–4.67).

Conclusion

The increased risk of congenital anomalies for women taking asthma medication is small with little confounding by maternal age or socioeconomic status. The study confirmed the association of inhaled corticosteroids with anal atresia found in earlier research and found potential new associations with combination treatment. The potential new associations should be interpreted with caution due to the large number of comparisons undertaken.

Tweetable abstract

This cohort study found a small increased risk of congenital anomalies for women taking asthma medication.

This cohort study found a small increased risk of congenital anomalies for women taking asthma medication.

Timing of motor milestones achievement and development of overweight in childhood: a study within the Danish National Birth Cohort

BACKGROUND

Overweight may hinder achievement of gross motor milestones and delayed achievement of milestones may increase the risk of later overweight for reasons involving physical activity and the building of lean body mass.

OBJECTIVE

To investigate whether increased birth weight and body mass index (BMI) at 5 months is associated with the achievement of the ability to sit up and walk and whether delayed achievement of these milestones is associated with overweight at age 7 years.

METHODS

We used data from the Danish National Birth Cohort on 25,148 children born between 1998 and 2003. Follow-up took place from 2003 to 2010. Mean age at follow-up was 7.04 years. We used logistic and linear regression analyses.

RESULTS

Birth weight and BMI at 5 months were marginally associated with earlier achievement of the ability to sit up and walk (regression coefficients between -0.027 months; [CI -0.042; -0.013] and -0.092 months [CI -0.118; -0.066]). Age in months of sitting and walking were not associated with overweight at age 7 years (ORs between 0.97 [CI 0.95-1.00] and 1.00 [CI 0.96-1.04]). Later achievement of sitting and walking predicted lower BMI at age 7 years (ln-BMI -z-scores between -0.023 [CI -0.029; -0.017] and -0.005 [CI -0.015; 0.005)).

CONCLUSIONS

All observed associations were of negligible magnitude and we conclude that birth weight or BMI at age 5 months and motor milestones appear largely independent of each other and that timing of achievement of motor milestones seems not to be associated with later overweight or increased BMI.

Disparities in pre-eclampsia and eclampsia among immigrant women giving birth in six industrialised countries

Objective

To assess disparities in pre-eclampsia and eclampsia among immigrant women from various world regions giving birth in six industrialised countries.

Design

Cross-country comparative study of linked population-based databases.

Setting

Provincial or regional obstetric delivery data from Australia, Canada, Spain and the USA and national data from Denmark and Sweden.

Population

All immigrant and non-immigrant women delivering in the six industrialised countries within the most recent 10-year period available to each participating centre (1995–2010).

Methods

Data was collected using standardised definitions of the outcomes and maternal regions of birth. Pooled data were analysed with multilevel models. Within-country analyses used stratified logistic regression to obtain odds ratios (OR) with 95% confidence intervals (95% CI).

Main outcome measures

Pre-eclampsia, eclampsia and pre-eclampsia with prolonged hospitalisation (cases per 1000 deliveries).

Results

There were 9 028 802 deliveries (3 031 399 to immigrant women). Compared with immigrants from Western Europe, immigrants from Sub-Saharan Africa and Latin America & the Caribbean were at higher risk of pre-eclampsia (OR: 1.72; 95% CI: 1.63, 1.80 and 1.63; 95% CI: 1.57, 1.69) and eclampsia (OR: 2.12; 95% CI: 1.61, 2.79 and 1.55; 95% CI: 1.26, 1. 91), respectively, after adjustment for parity, maternal age and destination country. Compared with native-born women, European and East Asian immigrants were at lower risk in most industrialised countries. Spain exhibited the largest disparities and Australia the smallest.

Conclusion

Immigrant women from Sub-Saharan Africa and Latin America & the Caribbean require increased surveillance due to a consistently high risk of pre-eclampsia and eclampsia.

Trends in socioeconomic differences in Finnish perinatal health 1991-2006

BACKGROUND

Socioeconomic differences in perinatal health decreased in Finland in the late 1990s. Whether the decreasing socioeconomic differences in perinatal health observed in Finland in the late 1990s have continued in 2000-6 was studied.

METHODS

The data were based on 965 443 births and 931 285 singletons recorded between 1991 and 2006 in the Finnish Medical Birth Register. Information on socioeconomic position was based on maternal occupation. Perinatal health was measured with six different indicators.

RESULTS

The proportions of preterm, low birthweight and SGA (small-for-gestational-age) births remained stable during the study period, but decreased for LGA (large-for-gestational-age) births and perinatal death. After adjustment for maternal background variables, the socioeconomic differences in preterm and low-birthweight births decreased in the late 1990s and remained low thereafter. In 2003-6, blue-collar workers had a 14% (95% CI 7% to 22%) higher risk for preterm birth and a 25% (95% CI 16% to 34%) higher risk for low birthweight than upper white-collar workers. For SGA, the socioeconomic differences remained unchanged, and the excess risk for blue-collar workers was 44% (95% CI 31% to 58%) in 2003-6. For LGA, the socioeconomic differences increased, and the highest excess risks were obtained among lower white-collar (23%, 95% CI 15% to 33%) and blue-collar workers (24%, 95% CI 14% to 36%). The differences in perinatal mortality decreased until the late 1990s, but increased thereafter. In 2003-6, lower white-collar and blue-collar workers had the highest excess risks: 46% (95% CI 20% to 77%) and 44% (95% CI 13% to 83%), respectively.

CONCLUSIONS

The trends in social inequality in perinatal health outcomes were diverging by indicator. The positive trend on diminishing socioeconomic differences found in the 1990s seems to have come to an end.

Does leisure time physical activity in early pregnancy protect against pre-eclampsia? Prospective cohort in Danish women

OBJECTIVE

To examine the association between physical activity in early pregnancy and risk of pre-eclampsia.

DESIGN

Prospective cohort.

SETTING

Denmark.

POPULATION

A total of 85,139 pregnant Danish women, recruited between 1996 and 2002.

METHODS

The authors assessed leisure time physical activity in first trimester by a telephone interview and categorised women a priori into seven groups: 0 (reference), 1-44, 45-74, 75-149, 150-269, 270-419 and 420+ minutes/week. Pre-eclampsia diagnoses were extracted from the Danish National Patient Registry. A number of potential confounders were adjusted for by logistic regression.

MAIN OUTCOME MEASURES

Pre-eclampsia and severe pre-eclampsia.

RESULTS

The two highest physical activity levels were associated with increased risk of severe pre-eclampsia compared with the nonexercising group, with adjusted odds ratios of 1.65 (95% CI: 1.11-2.43) and 1.78 (95% CI: 1.07-2.95), whereas more moderate levels of physical activity (1-270 minutes/week) had no statistically significant association with risk of pre-eclampsia (total n = 85,139).

CONCLUSIONS

We were unable to document a protective effect of leisure time physical activity against pre-eclampsia. Our data even suggest that leisure time physical activity exceeding 270 minutes/week in first trimester may increase risk of severe pre-eclampsia.

Use of nicotine replacement therapy during pregnancy and stillbirth: a cohort study

OBJECTIVE

The objective of this study was to examine whether the use of nicotine replacement therapy (NRT) during pregnancy increases the risk of stillbirth.

DESIGN

Cohort study with prospective data.

SETTING

Denmark 1996-2002.

POPULATION

A total of 87,032 singleton pregnancies enrolled in the Danish National Birth Cohort for which information on NRT use as well as smoking was available.

METHODS

Outcome of pregnancy was identified by register linkage, with <1% loss to follow up. We conducted Cox regression analyses to estimate the hazard ratio (HR) and 95% CI of stillbirth according to the use of NRT, type of NRT use and a combination of NRT use and smoking.

MAIN OUTCOME MEASURES

Stillbirth, defined as delivery of a dead fetus after 20 completed weeks of gestation.

RESULTS

A total of 495 pregnancies (5.7 in 1000 births) ended in stillbirth, 8 of which were among NRT users (4.2 in 1000 births). After adjustment for confounders, women who used NRT during pregnancy had a HR of 0.57 (95% CI 0.28-1.16) for stillbirth compared with those who did not use NRT. Smoking during pregnancy was associated with an increased risk of stillbirth (HR 1.46, 95% CI 1.17-1.82), while women who both smoked and used NRT had a HR of 0.83 (95% CI 0.34-2.00) compared with nonsmoking women who did not use NRT.

CONCLUSION

Our study does not indicate that use of NRT during pregnancy increases the risk of stillbirth.

Leisure time physical exercise during pregnancy and the risk of miscarriage: a study within the Danish National Birth Cohort

OBJECTIVE

To examine the association between leisure time physical exercise during pregnancy and the risk of miscarriage.

DESIGN

Prospective study with elements of retrospective data collection.

SETTING

Denmark 1996-2002.

POPULATION

A total of 92,671 pregnant women enrolled in the Danish National Birth Cohort and interviewed subsequently.

METHODS

Data on exercise during pregnancy and potential confounders were obtained through computer-assisted telephone interviews either during pregnancy or after an early miscarriage. Outcome of pregnancy was identified by register linkage. Using Cox regression analysis, we estimated the hazard ratio (HR) of miscarriage according to weekly amount of exercise and the type of exercise. The HR was estimated for <11, 11-14, 15-18, and 19-22 weeks of gestation, respectively.

MAIN OUTCOME MEASURES

Miscarriage, defined as fetal loss before 22 completed weeks of gestation.

RESULTS

A stepwise increasing relation was found between amount of exercise and risk of miscarriage, where risk of miscarriage increased by amount of exercise up to HR = 3.7 (95% CI 2.9-4.7) for women who exercised more than 7 hours per week compared with nonexercisers. Particularly 'high-impact exercise' was associated with an increased risk of miscarriage. No association was seen between exercise and risk of miscarriage after 18 weeks of gestation.

CONCLUSIONS

This study suggests that exercise early in pregnancy is associated with an increased risk of miscarriage. The results should, however, be interpreted cautiously as potential bias arising from retrospective data collection may explain part of the association.

Impact of the sex of first child on the prognosis in secondary recurrent miscarriage

BACKGROUND

The carriage of a male fetus often initiates maternal immunological reactions against male-specific minor histocompatibility (HY) antigens, which, in theory, could result in subsequent recurrent miscarriage (RM).

METHODS

Information about subsequent pregnancy outcome was procured among 182 women with RM after a birth (secondary RM) referred since 1986 using questionnaires, telephone interviews and registers.

RESULTS

Significantly more of the women had had a male first-born as compared with a female first-born (110 versus 72; P < 0.02). By January 2002, 58% of those who had a male first-born had given birth to a second live infant compared with 76% of those who previously had had a female first-born (P = 0.01). Women in the former group had a significantly lower chance of having a second child than those in the latter (adjusted hazard ratio 0.59; 95% confidence interval 0.41-0.86). The number of miscarriages after admission and the risk of secondary infertility were significantly greater in women with a male first-born than among those with a female first-born (P < 0.001 and P = 0.02; respectively).

CONCLUSIONS

A male first-born seems to be associated with a less favourable reproductive potential among women with secondary RM. Maternal immunization against HY antigens may be responsible for these findings.