Maternal Smoking Status in Successive Pregnancies and Risk of Having a Small for Gestational Age Infant

Associations between term cesarean delivery in the first pregnancy and second-pregnancy preterm delivery

INTRODUCTION

Cesarean delivery has been shown to increase the risk of preterm delivery in future pregnancies. The association could be a direct result of the procedure, or because the indications that led to the cesarean delivery also increase the risk of preterm delivery in later pregnancies.

MATERIAL AND METHODS

298 901 mothers with first and second singleton deliveries from 1999 to 2020 were investigated using data from the Medical Birth Registry of Norway linked with Statistics Norway. The mothers were categorized by mode of cesarean delivery (total, emergency and planned) and vaginal delivery at term in the first pregnancy. We used log-binomial regression models to estimate relative risks with 95% confidence intervals (CI) of iatrogenic and spontaneous preterm delivery <37 gestational weeks in the second pregnancy. Second, we explored the role of recurrent placental disease in preterm delivery by comparing estimates in mothers with placental disease in neither or both pregnancies.

RESULTS

8243 mothers (2.8%) had a preterm delivery in the second pregnancy. The adjusted relative risk (aRR) of preterm delivery was 1.24 (95% CI 1.17-1.32) after cesarean compared with vaginal delivery in the first pregnancy. The association was stronger in previous planned compared with emergency cesarean delivery (aRR 1.52, 95% CI 1.30-1.77 and aRR 1.21, 95% CI 1.14-1.29, respectively). Spontaneous preterm delivery was not associated with the previous mode of delivery; the risk was confined to iatrogenic preterm delivery after both emergency and planned cesarean delivery (aRR 1.69, 95% CI 1.52-1.87 and aRR 2.65, 95% CI 2.12-3.30, respectively). Mothers with placental disease in both pregnancies had a sixfold increased risk of preterm delivery in the second pregnancy compared with mothers with no placental disease, however, the association between mode of delivery and subsequent preterm delivery was similar in mothers with and without placental disease in the pregnancies.

CONCLUSIONS

Compared with vaginal term delivery in the first pregnancy, cesarean delivery increases the risk of iatrogenic, but not spontaneous preterm delivery in the next pregnancy. Although strongly associated with preterm delivery, placental disease had limited influence on the estimates.

Insights into Prevention of Health Complications in Small for Gestational Age (SGA) Births in Relation to Maternal Characteristics: A Narrative Review

Small for gestational age (SGA) births are a significant clinical and public health issue. The objective of this review was to summarize maternal biological and socio-demographic factors and preventive strategies used to reduce the risk of SGA births. A literature search encompassing data from the last 15 years was conducted using electronic databases MEDLINE/PubMed, Google Scholar and Scopus to review risk factors and preventive strategies for SGA. Current evidence shows that primiparity, previous stillbirths, maternal age ≤24 and ≥35 years, single motherhood, low socio-economic status, smoking and cannabis use during pregnancy confer a significant risk of SGA births. Studies on alcohol consumption during pregnancy and SGA birth weight are inconclusive. Beneficial and preventive factors include the "Mediterranean diet" and dietary intake of vegetables. Periconceptional folic acid supplementation, maternal 25-hydroxyvitamin D, zinc and iron levels are partly associated with birth weight. No significant associations between COVID-19 vaccinations and birthweight are reported. A midwifery-led model based on early and extensive prenatal care reduces the risk of SGA births in women with low socio-economic status. Major preventive measures relate to the awareness of modifiable and non-modifiable risk factors of SGA, leading to changes in parents' lifestyles. These data support that education, monitoring during pregnancy, and implementing preventive strategies are as important as biological determinants in risk reduction of SGA births.

New insights into smoking and urinary tract infections during pregnancy using pregnancy-pair design: A population-based register study

INTRODUCTION

Pregnancy itself predisposes to urinary tract infections (UTI). There appears to be a higher prevalence of infections and genitourinary diseases among pregnant smokers than among non-smokers. The present study is a retrospective observational register study aiming to investigate whether maternal smoking is associated with the prevalence of UTIs during pregnancy by utilizing a pregnancy-pair analysis.

MATERIAL AND METHODS

Information about pregnancies and maternal smoking was obtained from the Finnish Medical Birth Register. The study sample consisted of all singleton pregnancies (n = 723 433) of women giving birth between January 2006 and December 2018 in Finland. Information on maternal smoking was collected in three categories: (1) non-smoking; (2) quit smoking during the first trimester; and (3) continued smoking throughout the pregnancy. Information about maternal UTI diagnoses during pregnancy was received from the Hospital Discharge Register and the Medical Birth Register. UTIs were categorized as lower and upper UTIs according to the International Statistical Classification of Diseases and Related Health Problems (ICD)-10 diagnosis codes. Risks were calculated as odds ratios (OR) by logistic regression with 95% confidence intervals (CI) further adjusted for maternal characteristics (aOR). Finally, pregnancy-pair analyses were performed: mothers who had changed smoking status (no smoking/any smoking) between consecutive pregnancies (n = 27 246 pregnancy-pairs) were analyzed as one cluster and compared with non-smokers.

RESULTS

Smokers had UTIs more often compared with the non-smokers. The association was even stronger among those who continued to smoke (aOR 1.60, 95% CI 1.51-1.70) than among those who smoked only during the first trimester (aOR 1.27, 95% CI 1.18-1.37) compared with non-smokers. In pregnancy-pair analysis, smoking was associated with upper UTIs during pregnancy (OR 1.49, 95% CI 1.05-2.12) compared with non-smokers, but after the adjustments this association was attenuated (aOR 1.27, 95% CI 0.88-1.82). No association in lower UTIs was observed in the pregnancy-pair design.

CONCLUSIONS

Maternal smoking was associated with a higher prevalence of UTIs during pregnancy in the standard comparison. The observed association was fully attenuated in the pregnancy-pair analysis, in which smoking was dichotomized. This study suggests that the association between maternal smoking during pregnancy and adverse maternal health effects might be more complex than previously thought.

Parents experience a sense of guilt when their newborn is diagnosed small for gestational age, SGA. A grounded theory study in Sweden

BACKGROUND

To become a parent of a child who is born small for gestational age can lead to challenges in addition to the newly acquired parenting role. There is currently a lack of knowledge regarding parents' experiences of having a child born small for gestational age.

PURPOSE

The purpose of this study was to describe the experience of becoming a parent of a child small for gestational age DESIGN AND METHOD: A qualitative inductive approach was chosen with grounded theory as a method, a strategic selection was used and individual interviews with open questions were performed.

RESULTS

The results showed that the parents expressed guilt over the child's size and focused on the ability to nourish their child to keep their unexpectedly small child alive. An experienced concern about the child's food intake could be seen throughout the entire interview material and the need for information was great. A common experience of the parents was that constant feeding of the child dominates their lives.

CONCLUSION

The conclusion is that the unexpectedly small size of the child awakens the parent's instinct to provide life-sustaining care and the parents need increased support and more information around the child's condition. This requires well-trained professionals, because parents to children born SGA often harbour feelings of unpreparedness and guilt.

PRACTICE IMPLICATIONS

Increased understanding and knowledge about the parents' experience of having a child born SGA, healthcare services can optimize the potential for better attachment between parent and child as well as offer appropriate support.

Maternal smoking behaviour across the first two pregnancies and small for gestational age birth: Analysis of the SLOPE (Studying Lifecourse Obesity PrEdictors) population-based cohort in the South of England

Maternal smoking is established to cause adverse birth outcomes, but evidence considering maternal smoking change across successive pregnancies is sparse. We examined the association between self-reported maternal smoking during and between the first two pregnancies with the odds of small for gestational age (SGA) birth (<10th percentile) in the second infant. Records for the first two pregnancies for 16791 women within the SLOPE (Studying Lifecourse Obesity PrEdictors) study were analysed. This is a population-based cohort of prospectively collected anonymised antenatal and birth healthcare data (2003-2018) in Hampshire, UK. Logistic regression was used to relate maternal smoking change to the odds of SGA birth in the second infant. In the full sample, compared to never smokers, mothers smoking at the start of the first pregnancy had higher odds of SGA birth in the second pregnancy even where they stopped smoking before the first antenatal appointment for the second pregnancy (adjusted odds ratio (aOR) 1.50 [95% confidence interval 1.10, 2.03]). If a mother was not a smoker at the first antenatal appointment for either her first or her second pregnancy, but smoked later in her first pregnancy or between pregnancies, there was no evidence of increased risk of SGA birth in the second pregnancy compared to never smokers. A mother who smoked ten or more cigarettes a day at the start of both of her first two pregnancies had the highest odds of SGA birth (3.54 [2.55, 4.92]). Women who were not smoking at the start of the first pregnancy but who subsequently resumed/began smoking and smoked at the start of their second pregnancy, also had higher odds (2.11 [1.51, 2.95]) than never smokers. Smoking in the first pregnancy was associated with SGA birth in the second pregnancy, even if the mother quit by the confirmation of her second pregnancy.

Evaluation of incomplete maternal smoking data using machine learning algorithms: a study from the Medical Birth Registry of Norway

Background

The Medical Birth Registry of Norway (MBRN) provides national coverage of all births. While retrieval of most of the information in the birth records is mandatory, mothers may refrain to provide information on her smoking status. The proportion of women with unknown smoking status varied greatly over time, between hospitals, and by demographic groups. We investigated if incomplete data on smoking in the MBRN may have contributed to a biased smoking prevalence.

Methods

In a study population of all 904,982 viable and singleton births during 1999–2014, we investigated main predictor variables influencing the unknown smoking status of the mothers’ using linear multivariable regression. Thereafter, we applied machine learning to predict annual smoking prevalence (95% CI) in the same group of unknown smoking status, assuming missing-not-at-random.

Results

Overall, the proportion of women with unknown smoking status was 14.4%. Compared to the Nordic country region of origin, women from Europe outside the Nordic region had 15% (95% CI 12–17%) increased adjusted risk to have unknown smoking status. Correspondingly, the increased risks for women from Asia was 17% (95% CI 15–19%) and Africa 26% (95% CI 23–29%). The most important machine learning prediction variables regarding maternal smoking were education, ethnic background, marital status and birth weight. We estimated a change from the annual observed smoking prevalence among the women with known smoking status in the range of − 5.5 to 1.1% when combining observed and predicted smoking prevalence.

Conclusion

The predicted total smoking prevalence was only marginally modified compared to the observed prevalence in the group with known smoking status. This implies that MBRN-data may be trusted for health surveillance and research.

Supplementary Information

Supplementary information accompanies this paper at 10.1186/s12884-020-03384-y.

Attention-deficit/hyperactivity disorder and smoking habits in pregnant women

Background

Attention-deficit/hyperactivity disorder (ADHD) has been associated with an increased risk of tobacco smoking, and more difficulties with smoking cessation compared to non-ADHD individuals. Women with ADHD may therefore show elevated rates of smoking during pregnancy.

Aims

To examine the association between ADHD and smoking habits among pregnant women in Sweden and Norway.

Methods

Women pregnant for the first time were identified in Sweden (n = 622,037), and Norway (n = 293,383), of which 1.2% (n = 7,444), and 1.7% (n = 4,951) were defined as having ADHD, respectively. Data on smoking habits were collected early and late in pregnancy.

Results

In Sweden, ADHD was associated with an increased risk of smoking early in pregnancy, adjusted risk ratio (adjRR) 2.69 (95% confidence interval, 2.58–2.81), and late in pregnancy, adjRR 2.95 (2.80–3.10). Similar findings were observed in the Norwegian data, early in pregnancy, adjRR 2.31 (2.21–2.40), and late in pregnancy, adjRR 2.56 (2.42–2.70). Women with ADHD were more likely to continue smoking during pregnancy, compared to women without ADHD, both in Sweden adjRR 1.13 (1.10–1.17), and in Norway, adjRR 1.16 (1.12–1.20). Having a sibling diagnosed with ADHD was associated with an increased risk of smoking early and late in pregnancy, in both Sweden and Norway.

Conclusions

Women with ADHD are considerably more likely to smoke early and late in (their first) pregnancy and are less likely to stop smoking between the two time points. Smoking, early and late in pregnancy, co-aggregates in families with ADHD. Smoking prevention and intervention programs should be targeted towards women with ADHD, specifically during their childbearing years, to ensure better mother and child outcomes.

Snus in pregnancy and infant birth size: a mother-child birth cohort study

Rationale

While recent studies show that maternal use of snus during pregnancy is increasing, the potential effects on infant birth size is less investigated, with conflicting results.

Objectives

We aimed to determine if maternal use of snus during pregnancy influences the infant anthropometric and proportional size measures at birth.

Methods

In 2313 mother–child pairs from the population-based, mother–child birth cohort PreventADALL (Preventing Atopic Dermatitis and ALLergies) in Norway and Sweden, we assessed nicotine exposure by electronic questionnaire(s) at 18 and 34 weeks of pregnancy, and anthropometric measurements at birth. Associations between snus exposure and birth size outcomes were analysed by general linear regression.

Results

Birthweight was not significantly different in infants exposed to snus in general, and up to 18 weeks of pregnancy in particular, when adjusting for relevant confounders including maternal age, gestational age at birth, pre-pregnancy body mass index, parity, fetal sex and maternal gestational weight gain up to 18 weeks. We found no significant effect of snus use on the other anthropometric or proportional size measures in multivariable linear regression models. Most women stopped snus use in early pregnancy.

Conclusion

Exposure to snus use in early pregnancy, with most women stopping when knowing about their pregnancy, was not associated with birth size. We were unable to conclude on effects of continued snus use during pregnancy because of lack of exposure in our cohort.

Snus use in pregnancy, reported by 7.1% of 2313 women, was not associated with infant birth size. As most women stopped snus use by 6 weeks gestational age, it was not possible to assess potential birth size effects of persistent use during pregnancy.http://bit.ly/2IG8Vnk

Smoking in pregnancy, cord blood cotinine and risk of celiac disease diagnosis in offspring

Ecological observations suggest an inverse relationship between smoking in pregnancy and celiac disease (CD) in offspring. While individual-level analyses have been inconsistent, they have mostly lacked statistical power or refined assessments of exposure. To examine the association between pregnancy-related smoking and CD in the offspring, as well as its consistency across data sets, we analyzed: (1) The Norwegian Mother and Child Cohort (MoBa) of 94,019 children, followed from birth (2000–2009) through 2016, with 1035 developing CD; (2) a subsample from MoBa (381 with CD and 529 controls) with biomarkers; and (3) a register-based cohort of 536,861 Norwegian children, followed from birth (2004–2012) through 2014, with 1919 developing CD. Smoking behaviors were obtained from pregnancy questionnaires and antenatal visits, or, in the MoBa-subsample, defined by measurement of cord blood cotinine. CD and potential confounders were identified through nationwide registers and comprehensive parental questionnaires. Sustained smoking during pregnancy, both self-reported and cotinine-determined, was inversely associated with CD in MoBa (multivariable-adjusted [a] OR = 0.61 [95%CI, 0.46–0.82] and aOR = 0.55 [95%CI, 0.31–0.98], respectively); an inverse association was also found with the intensity of smoking. These findings differed from those of our register-based cohort, which revealed no association with sustained smoking during pregnancy (aOR = 0.97 [95%CI, 0.80–1.18]). In MoBa, neither maternal smoking before or after pregnancy, nor maternal or paternal smoking in only early pregnancy predicted CD. In a carefully followed pregnancy cohort, a more-detailed smoking assessment than oft-used register-based data, revealed that sustained smoking during pregnancy, rather than any smoking exposure, predicts decreased likelihood of childhood-diagnosed CD.

Perinatal risks in female cancer survivors: A population-based analysis

Background/objectives

Advances in cancer management have resulted in improved survival rates, particularly in children and young adults. However, treatment may adversely affect reproductive outcomes among female cancer survivors. The objective of this study was to investigate their risk of adverse perinatal outcomes compared to the general population.

Design/methods

We performed a population-based analysis, including all female cancer survivors diagnosed before the age of 40 years between 1981 and 2012. Pregnancy and perinatal complications were identified through linkage of the Scottish Cancer Registry with hospital discharge records based on the Community Health Index (CHI) database. We compared 1,629 female cancer survivors with a first ever singleton pregnancy after diagnosis, with controls matched on age, deprivation quintile, and year of cancer diagnosis selected from the general population (n = 8,899). Relative risks and 95%-confidence intervals of perinatal risks were calculated using log-binomial regression.

Results

Survivors were more likely to give birth before 37 weeks of gestation (relative risk (RR]) 1.32, 95%-CI 1.10–1.59), but did not show an increased risk of low birth weight (<2.5kg: RR 1.15, 95%-CI 0.94–1.39), and were less likely to give birth to offspring small for gestational age (RR 0.81, 95%-CI 0.68–0.98). Operative delivery and postpartum haemorrhage were more common but approached rates in controls with more recent diagnosis. The risk of congenital abnormalities was not increased (RR 1.01, 95%-CI 0.85–1.20).

Conclusion

Cancer survivors have an increased risk of premature delivery and postpartum haemorrhage, but their offspring are not at increased risk for low birth weight or congenital abnormalities. In recent decades there has been a normalisation of delivery method in cancer survivors, nevertheless careful management remains appropriate particularly for those diagnosed in childhood.