Infants with single umbilical artery studied in a national registry. General epidemiological characteristics

In this paper, registry data on infants born in Sweden between 1983 and 1986 are reviewed to describe the epidemiological characteristics of infants with single umbilical artery (SUA). During this period 372,066 births were registered with information on the number of umbilical vessels. Our data set contains 1782 SUA infants. The incidence at birth was: in multiple births 0.8%, in infants with chromosome anomalies 6.1% and in singletons without a known chromosome anomaly 0.46%. Incidence was higher in girls than in boys. There were no consistent seasonal variations in the date of presumed conception. Low birthweight (less than 2500 g) and preterm birth (less than 37 weeks) were seen more frequently in SUA singleton infants than in infants with three vessels. At any given gestation, SUA infants had a lower mean birthweight than infants with three vessels. The risk of having a SUA infant was increased in women over 40 years, and slightly increased at or above parity of three.     

Infants with single umbilical artery studied in a national registry. General epidemiological characteristics

Summary. In this paper, registry data on infants born in Sweden between 1983 and 1986 are reviewed to describe the epidemiological characteristics of infants with single umbilical artery (SUA). During this period 372 066 births were registered with information on the number of umbilical vessels. Our data set contains 1782 SUA infants. The incidence at birth was: in multiple births 0.8%, in infants with chromosome anomalies 6.1% and in singletons without a known chromosome anomaly 0.46%. Incidence was higher in girls than in boys. There were no consistent seasonal variations in the date of presumed conception. Low birthweight (<2500 g) and preterm birth (<37 weeks) were seen more frequently in SUA singleton infants than in infants with three vessels. At any given gestation, SUA infants had a lower mean birthweight than infants with three vessels. The risk of having a SUA infant was increased in women over 40 years, and slightly increased at or above parity of three.     

Perinatal and maternal risk factors for autism spectrum disorders in New South Wales, Australia

Background This study was commenced in 1999 with the aim of examining risk factors for autism using established population‐based data for comparison. Methods Cases were ascertained using active surveillance and compared with birth data. Results Four risk factors were found to be significantly associated with autism using binary logistic regression analysis; being male [adjusted odds ratio (OR) 4.7, 95% confidence interval (CI) 3.2–7.0], being born prematurely (adjusted OR 2.2, 95% CI 1.5–3.5), having maternal age ≥35 years (adjusted OR 1.7, 95% CI 1.2–2.4) and having a mother born outside Australia (adjusted OR 1.4, 95% CI 1.0–1.9). For analysis completed for pregnancies, rather than live births, multiple birth was also a significant risk factor for one or more children of the pregnancy to be affected by autism (adjusted OR 2.5, 95% CI 1.1–5.5). There was a statistically significant trend towards increasing risk with increasing risk factor ‘dose’ for gestational age (P = 0.019), multiple birth (P = 0.016) and maternal age (P < 0.001). For mother's country of birth the group with the highest risk were children of mother's born in south‐east or north‐east Asia. There was a non‐significant trend towards a higher proportion of children with developmental disability having risk factors. Conclusion Replication of risk factors from previous studies and a significant risk factor ‘dose’ effect add to growing evidence that maternal and perinatal factors are low magnitude risk factors for autism. The association between developmental disability and autism risk factors warrants further examination.     

Maternal smoking and congenital heart defects

The Swedish Child Cardiology Registry (CCR) and the Swedish Medical Birth Registry (MBR) were used to investigate a possible association between maternal smoking during pregnancy and congenital heart defects. Among 1,413,811 infants born in 1983–1996 with known smoking exposure in early pregnancy, 3384 infants with congenital heart defects were selected (458 term infants with persistent ductus arteriosus (PDA) identified from MBR or CCR, and 2926 infants with other heart defects, identified from CCR). After controlling for year of birth, maternal age, parity, and educational level, a weak, statistically significant association between all heart defects and maternal smoking was found (odds ratio (OR): 1.09; 95% confidence interval (CI): 1.01–1.19). When infants with isolated PDA were removed from the case group the significance disappeared (OR: 1.07; 95% CI: 0.98–1.17). For truncus abnormalities (OR: 1.23; 95% CI: 1.02–1.49), atrial septal defects (OR: 1.63; 95% CI: 1.04–2.57), and PDA (OR: 1.30; 95% CI: 1.05–1.62), a rather strong effect of maternal smoking was indicated. The increased OR for PDA remained when gestational duration and intrauterine growth was also controlled for. Further research based on independent data sets is needed to conclude whether the risk estimates for maternal smoking are true and truly differ between the groups. The classification system used (with 24 classes) is described in enough detail to permit a repetition of the study.     

Infants with single umbilical artery studied in a national registry. 2: Survival and malformations in infants with single umbilical artery

Registry data on all infants born in Sweden between 1983 and 1986 are reviewed to describe perinatal mortality and malformation rate of infants with single umbilical artery (SUA). Since SUA is much more common in infants with chromosomal anomalies and in twins this analysis is confined to the 1694 singletons who were not recorded as having chromosomal anomalies. There was significantly increased risk of perinatal mortality among these infants largely due to an increased frequency of congenital malformations, low birthweight and preterm delivery. Nevertheless, at least 36% of the perinatal mortality occurred in the absence of malformations or low birthweight. We found the overall risk of severe malformation in SUA infants to be increased 4.3 times. Some malformations were especially common, such an anorectal atresia and oesophageal atresia.     

Extreme prematurity and school outcomes

The purpose of this study was to assess the impact of extreme prematurity on three global measures of school outcomes. Using a matched cohort design, exposed infants comprised all surviving singleton infants < or = 28 weeks gestation born at one regional neonatal intensive care hospital between 1983 and 1986 (n = 132). Unexposed infants comprised randomly selected full-term infants (> or = 37 weeks gestation) frequency matched on date of birth, zip code and health insurance. All children were selected from a regional tertiary children's centre serving western New York population. Standardised telephone interviews elicited information on grade repetition, special education placement and use of school-based services. Unconditional logistic regression was used to estimate odds ratios (OR) and corresponding 95% confidence intervals (CI) adjusted for potential confounders for children without major handicaps. Extreme prematurity was associated with a significant increase in risk of grade repetition (OR = 3.22; 95% CI = 1.63, 6.34), special education placement (OR = 3.16; 95% CI = 1.14, 8.76) and use of school-based services (OR = 4.56; 95% CI = 1.82, 11.42) in comparison with children born at term, even after controlling for age, race, maternal education, foster care placement and the matching factors. These findings suggest that survivors of extreme prematurity remain at risk of educational underachievement.     

Expressive vocabulary in 18-month-old children in relation to demographic factors, mother and child characteristics, communication style and shared reading

Background Previous research has elucidated the associations between children's language development and reading habits, and maternal education, communication style, gender and birth order. Research including maternal age and child temperament is more scarce. We studied the associations of all these factors with children's expressive vocabulary and reading habits. We also analysed the relationships of reading with expressive vocabulary, and effect sizes associated with frequent reading. Methods Questionnaires were completed by mothers of 1091 children aged 17–19 months visiting the Swedish Child Health Services. Expressive vocabulary was assessed by the Swedish Communication Screening at 18 months, a screening version of McArthur‐Bates Communicative Development Inventories. Mother's perception of ability to communicate was measured by a scale constructed ad hoc from the International Child Development Programmes, a parent education curriculum. Bates' ‘difficultness’ scale was used to assess temperament. Results Good communication, low maternal age, female gender and frequent reading were significantly associated with expressive vocabulary. High maternal education, good communication, higher maternal age, female gender and being a first‐born child were significantly associated with frequent reading. Reading at least 6 times/week added more than 0.3 SD in vocabulary regardless of gender and communication. Conclusions The findings support the importance of reading and communication quality to early language development. Knowledge of the relationship between children's vocabulary and book reading in a context of joint attention is both theoretically and practically valuable to speech and language pathologists, pre‐school teachers, child health workers and other professionals.     

Low rates of predominant breastfeeding in hospital after gestational diabetes,particularly among Indigenous women in Australia

Objectives: To investigate rates of ‘any’ and ‘predominant’ breastfeeding in hospital among Indigenous and non‐Indigenous women with and without gestational diabetes mellitus (GDM). Methods: A retrospective study of singleton infants born from July 2007 to December 2010 at Cairns Hospital, Australia, following GDM pregnancy, using linked hospital and birth data (n=617 infants), with a subsample of medical record reviews (n=365 infants). Aggregate data were used to compare to breastfeeding rates among infants born following non‐GDM pregnancy (n=7,894 infants). Results: More than 90% of all women reported any breastfeeding before hospital discharge. About 80% of women without GDM reported predominant breastfeeding. Despite significant increases over time (p<0.0001), women with GDM were less likely to predominantly breastfeed (OR 0.32, 95%CI 0.27–0.38, p<0.0001); with lower rates among Indigenous women (53%) compared with non‐Indigenous (60%) women (OR 0.78, 0.70–0.88, p<0.0001); and women having a caesarean birth or pre‐term infant. Conclusions: Rates of predominant in‐hospital breastfeeding were lower among women with GDM, particularly among Indigenous women and women having a caesarean or pre‐term birth. Implications: Strategies are needed to support predominant in‐hospital breastfeeding among women with GDM.     

The impact of maternal smoking during pregnancy on delivery outcome

BACKGROUND: Maternal smoking during pregnancy is associated with pre-term birth, intrauterine growth retardation, a small head circumference, a low Apgar score at 5 min and stillbirths and neonatal deaths. This study was undertaken in order to investigate the impact of maternal smoking during pregnancy when all these outcomes were considered. METHODS: With the use of the Swedish Medical Birth Registry, infants in any one of the above mentioned outcome groups were selected from 1,413,811 infants born between 1983 and 1996 with known smoking exposure in early pregnancy. Confounders such as year of birth, maternal age, parity and educational level were controlled for. The attributable risk of maternal smoking on the various negative delivery outcomes was obtained by application of the risk estimates to population counts. RESULTS: The present study confirmed the associations between maternal smoking and the miscellaneous outcomes mentioned above with high significance. The odds ratios (with 95% confidence intervals) for maternal smoking (< 10 cigarettes/day and > or = 10 cigarettes/day) for any one of the outcomes were 1.39 (1.37-1.41) and 1.65 (1.62-1.68) respectively (dose-response p < 0.001). The number of attributable cases caused by maternal smoking was estimated at 15,000, which represents 9% of all cases and 1% of all infants born in Sweden during the study period. CONCLUSION: Maternal smoking during pregnancy accounts for a substantial part of various negative delivery outcomes.     

Maternal occupation and congenital heart defects: a case-control study

Summary This paper reports a Swedish analysis of the possible effect of maternal occupation on the occurrence of congenital heart defects. The analysis included 3324 infants (1108 cases and 2216 controls) born during the period 1982–1986. Information on maternal occupation was retrieved using two sources: the 1985 census and the Medical Birth Registry. A comparison between these two sources using the information on mothers of 756 infants born in 1986 showed a good concordance although 11% of the women were reported with a different employment status. No association appeared between the type of maternal occupation and the occurrence of infant congenital heart defects although some odds ratios were slightly above 1.     

Perinatal risk factors for infantile autism

BACKGROUND: Etiologic hypotheses in infantile autism suggest a strong genetic component, as well as possible environmental risks linked to early fetal development. We evaluated the association of maternal, pregnancy, delivery, and infant characteristics and risk of infantile autism. METHODS: We conducted a case-control study nested within a population-based cohort (all Swedish children born in 1974-1993). We used prospectively recorded data from the Swedish Birth Register, which were individually linked to the Swedish Inpatient Register. Cases were 408 children (321 boys and 87 girls) discharged with a main diagnosis of infantile autism from any hospital in Sweden before 10 years of age in the period 1987-1994, plus 2,040 matched controls. Conditional logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: The risk of autism was associated with daily smoking in early pregnancy (OR = 1.4; CI = 1.1-1.8), maternal birth outside Europe and North America (OR = 3.0; CI = 1.7-5.2), cesarean delivery (OR = 1.6; CI = 1.1-2.3), being small for gestational age (SGA; OR = 2.1; CI = 1.1-3.9), a 5-minute Apgar score below 7 (OR = 3.2, CI = 1.2-8.2), and congenital malformations (OR = 1.8, CI = 1.1-3.1). No association was found between autism and head circumference, maternal diabetes, being a twin, or season of birth. CONCLUSIONS: Our findings suggest that intrauterine and neonatal factors related to deviant intrauterine growth or fetal distress are important in the pathogenesis of autism.     

The neonatal period: A missed opportunity for the prevention of iron deficiency and its associated neurological consequences?

Iron deficiency is the most common micronutrient deficiency worldwide. Iron is essential for the development of multiple organ systems, most especially the developing brain. Iron deficiency, particularly during sensitive periods of brain development, such as in early childhood, is associated with long‐lasting adverse consequences for cognition, motor function and behaviour. Little consideration has been given to iron deficiency in newborn infants and its potential health consequences. Fetal iron accretion is compromised by pregnancy complications such as pre‐term birth and gestational diabetes mellitus, and our work has identified an increased risk of low iron stores at birth from maternal lifestyle factors such as smoking and obesity. Early‐life events, including Caesarean section delivery, further add to the cumulative risk of neonatal iron deficiency, which can persist throughout infancy into early childhood. While investigations into the long‐term neurological consequences of neonatal iron deficiency are limited, there is evidence of poorer memory, motor function and language ability in children born iron deficient. Recently, we also identified significant behavioural consequences of neonatal deficiency persisting from 2 to 5 years of age, with effects particularly apparent in ‘high‐risk’ children born to obese or smoking mothers or delivered by Caesarean section. Interventions targeting the fetal/neonatal period could therefore represent a key opportunity for the prevention of iron deficiency and its associated long‐term health consequences. A dual approach is required, comprising public health strategies targeting prevention, to improve health in women of reproductive age, and the development of screening strategies for the early detection of iron deficiency in newborn infants.     

Splitting bodies/selves: women’s concepts of embodiment at the moment of birth

Little sociological research has focused specifically on the moment of birth. In this article we draw upon interview data with women who had very recently given birth for the first time to explore the ways in which they described both their own embodiment and that of their infants at this time. We use the term ‘the body‐being‐born’ to describe the liminality and fragmentation of the foetal/infant body as women experience it when giving birth. The study found that mode of birth was integral to the process of coming to terms with this body during and following birth. The women who gave birth vaginally without anaesthesia experienced an intense physicality as they felt their bodies painfully opening as the ‘body‐being‐born’ forced its way out. In contrast the women who had had a Caesarean section tended to experience both their own bodies and those of their infants as absent and alienated. Most of the women took some time to come to terms with the infant once it was born, conceptualising it as strange and unknown, but those who delivered by Caesarean section had to work even harder in coming to terms with the experience.     

Maternal smoking during pregnancy and school performance at age 15

BACKGROUND: Smoking during pregnancy has been suggested to have long-term consequences for neuropsychologic development in the offspring, including behavioral problems, attention deficit disorders, and antisocial behavior. Also, findings from several studies indicate an association with impaired cognitive function in the children. METHODS: In a population-based Swedish cohort study, we examined possible associations between maternal smoking in pregnancy and educational achievement in the offspring at age 15 years among more than 400,000 male and female students born 1983 through 1987. Generalized estimating equation models were used to evaluate associations of maternal smoking, other maternal characteristics, and birth characteristics with school performance. Odds ratios (ORs) were used as a measure of risk. RESULTS: In a model adjusted for maternal characteristics, maternal smoking compared with no tobacco use during pregnancy was associated with an increased risk of poor scholastic achievement: for 1-9 cigarettes per day, the OR was 1.59 (95% confidence interval = 1.59-1.63) and for 10 or more cigarettes per day, the OR was 1.92 (1.86-1.98). These risks remained unchanged when we also adjusted for smoking-related pregnancy outcomes such as fetal growth restriction and preterm birth. However, if the mother had smoked in her first pregnancy, but not in her second pregnancy, the younger sibling was also at increased risk of poor school performance. CONCLUSION: Observed associations between maternal smoking during pregnancy and poor cognitive performance in the offspring might not be causal. We suggest that associations reported in earlier studies may instead reflect the influence of unmeasured characteristics that differ between smokers and nonsmokers.     

Infants with single umbilical artery studied in a national registry. 3: A case control study of risk factors

Summary. This case control study reports associations between single umbilical artery (SUA) in newborns and some maternal biological characteristics. The study is based on chromosomally normal singleton infants born in Sweden between 1983 and 1990. Information on the maternal characteristics studied was obtained prospectively. There were 2920 cases identified and 5840 controls were selected. An association was found with: previous perinatal death, retained placenta, placenta praevia, maternal diabetes, epilepsy and hydramnios. Increased odds ratios were seen also for spontaneous abortion and abruptio placentae but did not reach statistical significance. No association was found with previous induced abortion, involuntary childlessness, or the use of contraceptives after the last menstrual period.     

Socioeconomic factors and the risk of anencephaly in a Mexican population: a case-control study

OBJECTIVE: The study was designed to evaluate the association between socioeconomic level (as measured by maternal education, maternal occupation, and monthly family income) and anencephaly. METHODS: The authors conducted a case-control study using data from the Epidemiological Surveillance System Register for Neural Tube Defects for three states of the Mexican Republic: Puebla, Guerrero and the State of Mexico. Mothers of 151 cases of infants born with anencephaly and mothers of 151 control infants born during the period March 2000 to February 2001 were interviewed about their socioeconomic characteristics and other factors including reproductive history, use of prenatal care, use of tobacco and alcohol, fever during pregnancy, and folic acid supplementation. RESULTS: After adjustment for potential confounders, a risk gradient was seen with decreasing maternal education. Women with less than a primary school education (adjusted odds ratio [OR]=3.0; 95% confidence interval [CI] 1.2, 7.6) and women who had completed primary school but had not completed junior high school (adjusted OR=2.2; 95% CI 0.9, 5.7) had higher risks of giving birth to an infant with anencephaly, compared to women with a higher educational level. A monthly income < or = 1,000 pesos (approximately dollars 100 U.S.) was also associated with a higher risk of anencephaly (OR=2.5; 95% CI 1.2, 5.1). Women employed in industry or agriculture during the acute risk period (three months prior to conception to one month after conception) had a risk 6.5 times (95% CI 1.4, 29.6) that of professional and business women. CONCLUSIONS: This study helps to identify groups that may be especially vulnerable to this type of congenital malformation so that primary and secondary preventive strategies can be targeted to these groups.     

Respiratory distress syndrome in preterm infants and risk of epilepsy in a Danish cohort

Infant respiratory distress syndrome (IRDS) may be complicated by intracerebral hemorrhage, a known trigger of epilepsy. However, few data exist on long term epilepsy risk following IRDS. We therefore examined the association between IRDS in preterm infants and childhood epilepsy. We conducted a population-based cohort study using individual-level data linkage among nationwide registries. All infants born at 32–36 weeks of gestation in 1978–2009 were identified in the Medical Birth Registry. We identified children with IRDS and those with epilepsy using the Danish National Patient Registry. We computed the cumulative incidence of epilepsy with follow-up from birth until epilepsy, emigration, death, age 15, or December 31, 2014. We used Cox’s regression analysis to compute hazard ratios comparing children with and without IRDS, adjusting for sex, birth year, gestational age, multiplicity, major malformations, and maternal age. We identified 95,026 infants, of whom 6426 (6.8%) had IRDS. The cumulative incidence of epilepsy was 3.4% by age 15 in children with IRDS and 2.1% in children without IRDS. The adjusted hazard ratio of epilepsy among children with IRDS compared to those without was 1.4 (95% CI 1.2–1.6). When we restricted the IRDS cohort to children with no simultaneous morbidities that had clinical symptoms overlapping with IRDS, the overall adjusted HR was 1.1 (95% CI 0.9–1.4). In children born preterm at 32–36 weeks’ gestation, IRDS was associated with increased risk of childhood epilepsy.     

Risk factors in term children for visual impairment without a known prenatal or postnatal cause

Risk factors were studied for visual impairment in children without known pre- or postnatal cause, for a decrease of visual acuity. Children born at term 1979-98 and with a visual impairment were identified from the Swedish Register of Visually Impaired Children and data were linked with the Swedish Medical Birth Registry. Maternal characteristics such as maternal age, parity, maternal smoking habits in early pregnancy, maternal education, nationality, and subfertility were studied as well as maternal diagnoses such as pre-eclampsia, prolonged second stage of labour, abruptio placentae, and placenta praevia. Mode of delivery was analysed as well as birthweight, and birthweight in relation to gestational age. Abruptio placentae turned out to be the strongest risk factor (OR = 8.24 [95% CI 5.01, 13.51]). Smoking did not give a statistically significant increased risk. There is an increased risk with breech delivery (OR = 2.01 [95% CI 1.28, 3.17]). Pre-eclampsia was associated with an increased risk (OR = 2.22 [95% CI 1.46, 3.38]). There is also an increase in risk at low birthweight and small-for-gestational-age as well as birthweight > 4 kg and large-for-gestational-age. In this study we found that risk factors particularly worth noticing in term children with a presumed perinatal cause of visual impairment are abruptio placentae, pre-eclampsia, excessively low as well as excessively high birthweight, and breech delivery, a fact worth noticing in current discussion on risks, advantages or excessive exploitation of caesarean section.     

Neighbourhood greenness and birth outcomes in a Swedish birth cohort – A short communication

The present study investigated whether associations between greenness and birth outcomes can be detected in children belonging to a Swedish birth cohort (BAMSE). Normalized difference vegetation index (NDVI) within a 500 m buffer zone around maternal address was used as estimate of greenness. Ordinary least squares and quantile regression models were performed to investigate associations between neighbourhood NDVI and birthweight (n = 2619), birth length (n = 2490) and head circumference (n = 2243). Logistic regression analyses were used to detect the association between NDVI and odds of being born as “small-” or “large-for-gestational-age”. There were no clear associations between NDVI and birth weight in the total sample. However, in a suburban sub-sample, increased NDVI levels were significantly associated with elevated birthweight of small new-borns (β_{2nd percentile} = 276 g, 95% CI 61 to 492, p = 0.012), and significantly reduced the odds ratio (OR) for children being born as small-for-gestational-age (OR = 0.31 95% CI 0.1 to 1, p = 0.049). No significant associations were found between NDVI and birth length or head circumference. In conclusion, neighbourhood greenness appears not to be associated with birthweight as such, but rather decrease the odds of being born underweight, in particular in suburban areas.     

Developing a Maternally Linked Birth Dataset to Study the Generational Recurrence of Low Birthweight in Virginia

This paper examined the generational recurrence of low birthweight (LBW) among first-born singletons using a statewide maternally-linked birth dataset. An intergenerational dataset was created by linking 2005–2009 to 1960–1997 Virginia resident live birth data. Maternal information from the recent birth cohort was linked to infant information in the historic birth file using various combinations of mother’s name and birthdate. The linked dataset contained 170,624 records (87 % of all eligible records). The analysis dataset was limited to non-Hispanic black and non-Hispanic white first-born singleton infants linked to their mother’s own birth record (n = 69,702). Maternal birthweight was a significant predictor of LBW for first-born singletons. The birthweight distribution for both non-Hispanic black and non-Hispanic white infants was shifted toward lower birthweights for infants whose mothers were born LBW. Even after adjusting for known maternal risk factors in the current pregnancy, non-Hispanic black (AOR = 1.6 [95 % CI 1.4, 1.8]) and non-Hispanic white (AOR = 2.0 [95 % CI 1.8, 2.3]) infants had increased odds of being born LBW if their mother was born LBW. A mother’s early life experiences can impact the health of her children. These findings underscore the importance of applying a life course perspective to the prevention of LBW. Routine linkage of maternal and infant birth data is needed to strengthen the evidence base for policies and programs that address issues affecting maternal and child health throughout the life course.