Impact of multiple births and elective deliveries on the trends in low birth weight in Norway, 1967-1995

Caesarean Section Delivery Is Associated with Childhood Overweight and Obesity, Low Childbirth Weight and Postnatal Complications: A Cross-Sectional Study

Background and Objectives: In the last decades, simultaneously increasing trends have been recorded for both caesarean section delivery and childhood overweight/obesity around the world, which are considered serious public health concerns, negatively affecting child health. Aim: The present study aims to investigate whether caesarean section is associated with the increased rates of childhood overweight/obesity, low childbirth anthropometric indices and postnatal complications in pre-school age. Materials and Methods: This is a cross-sectional study in which 5215 pre-school children aged 2–5 years old were enrolled from nine different Greek regions after applying specific inclusion and exclusion criteria. Non-adjusted and adjusted statistical analysis was performed to assess the impact of caesarean section in comparison to vaginal delivery. Results: Children delivered by caesarean section were significantly more frequently overweight or obese at the age of 2–5 years, also presenting a higher prevalence of low birth weight, length and head circumference. Caesarean section was also associated with higher incidence of asthma and diabetes type I at the age of 2–5 years. In a multivariate analysis, caesarean section increased the risk of childhood overweight/obesity and low childbirth anthropometric indices even if adjusting for several childhood and maternal confounding factors. Conclusions: Increasing trends were recorded for both caesarean section delivery and childhood overweight/obesity, which are considered serious public health concerns. Caesarean section independently increased childhood overweight/obesity in pre-school age, highlighting the emergent need to promote health policies and strategies to inform future mothers about its short and long-term risks and that this mode of delivery should preferably be performed only when there are strong medical recommendations in emergency obstetric conditions.

Incidence, risk factors and consequences of preterm birth - findings from a multi-centric observational study for 14 months in Nepal

Background

Preterm birth is a worldwide epidemic and a leading cause of neonatal mortality. In this study, we aimed to evaluate the incidence, risk factors and consequences of preterm birth in Nepal.

Methods

This was an observational study conducted in 12 public hospitals of Nepal. All the babies born during the study period were included in the study. Babies born < 37 weeks of gestation were classified as preterm births. For the association and outcomes for preterm birth, univariate followed by multiple regression analysis was conducted.

Results

The incidence of preterm was found to be 93 per 1000 live births. Mothers aged less than 20 years (aOR 1.26;1.15–1.39) had a high risk for preterm birth. Similarly, education of the mother was a significant predictor for preterm birth: illiterate mothers (aOR 1.41; 1.22–1.64), literate mothers (aOR 1.21; 1.08–1.35) and mothers having basic level of education (aOR 1.17; 1.07–1.27). Socio-demographic factors such as smoking (aOR 1.13; 1.01–1.26), use of polluted fuel (aOR 1.26; 1.17–1.35) and sex of baby (aOR 1.18; 1.11–1.26); obstetric factors such as nulliparity (aOR 1.33; 1.20–1.48), multiple delivery (aOR 6.63; 5.16–8.52), severe anemia during pregnancy (aOR 3.27; 2.21–4.84), antenatal visit during second trimester (aOR 1.13; 1.05–1.22) and third trimester (aOR 1.24; 1.12–1.38), < 4 antenatal visits during pregnancy (aOR 1.49; 1.38–1.61) were found to be significant risk factors of preterm birth. Preterm has a risk for pre-discharge mortality (10.60; 9.28–12.10).

Conclusion

In this study, we found high incidence of preterm birth. Various socio-demographic, obstetric and neonatal risk factors were associated with preterm birth. Risk factor modifications and timely interventions will help in the reduction of preterm births and associated mortalities.

Trial registration

ISRCTN30829654.

Birth Weight and Cardiorespiratory Fitness Among Young Men Born at Term: The Role of Genetic and Environmental Factors

Background Preterm delivery and low birth weight are prospectively associated with low cardiorespiratory fitness (CRF). However, whether birth weight, within the at-term range, is associated with later CRF is largely unknown. Thus, the aim of the current study was to examine this issue and whether such association, if any, is explained by shared and/or nonshared familial factors. Methods and Results We conducted a prospective cohort study, including 286 761 young male adults and a subset of 52 544 siblings born at-term. Objectively measured data were retrieved from total population registers. CRF was tested at conscription and defined as the maximal load obtained on a cycle ergometer. We used linear and nonlinear and fixed-effects regression analyses to explore associations between birth weight and CRF. Higher birth weight, within the at-term range, was strongly associated with increasing CRF in a linear fashion. Each SD increase in birth weight was associated with an increase of 7.9 (95% CI, 7.8-8.1) and 6.6 (95% CI; 5.9-7.3) Wmax in the total and sibling cohorts, respectively. The association did not vary with young adulthood body mass index. Conclusions Birth weight is strongly associated with increasing CRF in young adulthood among men born at-term, across all categories of body mass index. This association appears to be mainly driven by factors that are not shared between siblings. Hence, CRF may to some extent be determined already in utero. Prevention of low birth weight, also within the at-term-range, can be a feasible mean of increasing adult CRF and health.

Tehran Survey of Potential Risk Factors for Multiple Births

Background

The multiple pregnancy incidence is increasing worldwide. This increased incidence is concerning to the health care system. This study aims to determine the frequency of multiple pregnancy and identify factors that affect this frequency in Tehran, Iran.

MATERIALS AND METHODS

This cross-sectional study included 5170 mothers in labor between July 6-21, 2015 from 103 hospitals with Obstetrics and Gynecology Wards. The questionnaire used in this study consisted of five parts: demographic characteristics; information related to pregnancy; information related to the infant; information regarding the multiple pregnancy; and information associated with infertility. We recruited 103 trained midwives to collect data related to the questionnaire from eligible participants through an interview and medical records review. Frequencies and odds ratios (OR) for the association between multiple pregnancy and the selected characteristics (maternal age, economic status, history of multiple pregnancy in first-degree relatives, and reproductive history) were computed by multiple logistic regression. Stata software, version 13 (Stata Corp, College Station, TX, USA) was used for all statistical analyses.

RESULTS

Multiple pregnancy had a prevalence of 1.48% [95% confidence interval (CI): 1.19-1.85]. After controlling for confounding variables, we observed a significant association between frequency of multiple pregnancy and mother's age (OR=1.04, 95% CI: 1.001-1.09, P=0.044), assisted reproductive technique (ART, OR=6.11, 95% CI: 1.7- 21.97, P=0.006), and history of multiple pregnancy in the mother's family (OR=5.49, 95% CI: 3.55-9.93, P=0.001).

CONCLUSION

The frequency of multiple pregnancy approximated results reported in previous studies in Iran. Based on the results, we observed significantly greater frequency of multiple pregnancy in older women, those with a history of ART, and a history of multiple pregnancy in the mother's family compared to the other variables.

Socio-economic risk factors for preterm birth in Norway 1999–2009

Aims: Preterm birth is a major cause of perinatal mortality and morbidity and is strongly associated with socio-economic factors. The objective of this study was to examine the associations of maternal education, marital status and ethnicity with preterm birth and to determine the extent to which such associations can be explained by the established risk factors of maternal age, parity and smoking. Methods: This was a register-based cohort study with data from the Medical Birth Registry of Norway 1999–2009 and Statistics Norway. The sample included all singleton spontaneous births in Norway from 1999 to 2009 ( n=494,073). The main outcome measure was preterm birth (gestational age <37 weeks). Results: Low maternal education and single motherhood were associated with preterm birth. After adjustment for the established risk factors, the excess risks were reduced, but remained statistically significant. The relative risk for low education was reduced from 1.50 to 1.36 and for single motherhood from 1.50 to 1.28. Women from Asia had a higher risk of preterm birth than Norwegian-born women (relative risk 1.29) with minor effects of adjustment. Conclusions: Several socio-economic risk factors are associated with preterm birth in Norway. In addition to the established risk factors, prenatal health care should focus on high-risk groups defined by maternal education, marital status and ethnicity.

Effects of maternal factors on birth weight in Japan

Objective. We investigated the possible factors related to the birth weight (BW) using the Japanese perinatal database. Methods. The live infants born at 37 to 41 weeks of gestation were enrolled in this study. Cases with diabetic pregnancy, preeclampsia, an anomalous fetus, and a fetus with chromosomal abnormalities were excluded. A multiple regression analysis for confounding factors and an analysis of covariance (ANCOVA) for comparing the BW in 2006 and 2010 were used for the statistical analysis. Results. The BW significantly decreased from 2950.8 g in 2006 (n = 27,723) to 2937.5 g in 2010 (n = 38,008) in the overall population, and this decrease was similar for male and female neonates. All confounding factors, except for the mode of delivery, affected the BW. Primiparity, smoking, and a female gender were related to the decrease in BW, whereas maternal age, maternal height, weight gain during pregnancy, BMI, the use of in vitro fertilization, induction of labor, and gestational duration were related to an increased BW. The ANCOVA showed that no significant change of the BW was seen between 2006 and 2010 (the difference was 2.164 g, P = 0.414). Conclusion. The gestational duration is the most important factor affecting the BW in singleton term infants.

The effect of an increase in the rate of multiple births on low-birth-weight and preterm deliveries during 1975-2008

BACKGROUND

Despite the rapid increase in the rate of multiple births due to the growth of reproductive medicine, there have been no epidemiologic studies of the secular trends in the impact of multiple births on the rates of low-birth-weight and preterm deliveries in Japan.

METHODS

Japanese vital statistics for multiple live births were obtained from the Ministry of Health, Labour and Welfare and reanalyzed. With singletons as the reference group, an analysis was performed of secular trends in relative risk and population attributable risk percent of low-birth-weight (<2500 grams), very-low-birth-weight (<1500 grams), and extremely-low-birth-weight (<1000 grams) deliveries, using 1975-2008 vital statistics, and of preterm deliveries (ie, before 37, 32, and 28 weeks), using 1979-2008 vital statistics.

RESULTS

The rate of multiple births doubled during the past 2 decades, and about 2% of all neonates are now multiples. The population attributable risk percent tended to increase during the same period for all variables, and was approximately 20% in 2008.

CONCLUSIONS

The public health impact of the rapid increase in multiple births remains high in Japan.

Trends in the prevalence of low birth weight in Okinawa, Japan: a public health perspective

AIM

To review the trends in low birth weight (LBW) in Japan and Okinawa and to discuss the public health implications of the trend.

METHODS

The statistical records of Japan and the Okinawa prefecture were reviewed to observe secular trends of LBW incidence rate and other health indicators. Literature researches were undertaken of English and Japanese language publications to complete the review.

RESULTS

The LBW rate in Japan declined until the 1970s, reaching a low point for the whole country in 1978-1979 when it was 5.2% (7.2% in Okinawa). In Okinawa the proportion of LBW declined from 8.1% in 1973 to 7.2 in 1978. Since 1980 the LBW rate has steadily increased to its current level of 9.3% in Japan and 10.9% in Okinawa. During this period, the prematurity rate has not increased and other indicators of child health have continued to improve.

CONCLUSION

Japan is unique among developed countries in that the LBW rate has almost doubled in the past three decades and the rate in Okinawa is 20% greater than the mainland. The health costs of this trend include the neonatal care of LBW infants and the increased risk of chronic disease in later life.

Secular trends in socio-economic status and the implications for preterm birth

The rate of preterm birth in the developed world has been shown to be increasing, in part attributable to obstetric intervention. It has been suggested that this may be a differential increase between socio-economic groups. We aimed to assess whether the preterm rate in Norway is different in socio-economic groups defined by maternal education, and to determine the extent to which a difference is attributable to a socio-economic differential in obstetrical intervention, in terms of caesarean section or induction of labour. We used data from the Medical Birth Registry of Norway from 1980 to 1998 with preterm rate as the outcome and maternal educational level, marital status and obstetric intervention as exposure variables. In multivariable analyses, adjustment was made for maternal age, year of birth and birth order, and secular trends were assessed according to year of birth. The preterm birth rate was highest in the lowest socio-economic group. An increase of 25.2% in the preterm rate was seen over the observation period. No apparent differential was seen in the increase of the crude preterm rates between socio-economic groups, although in multivariable analyses there was a significant interaction between socio-economic group and time, implying a stronger effect of low education towards the end of the observation period attributable to demographic change. In conclusion, the preterm birth rate increased over time, but was mainly due to an increase in obstetric interventions. No closing of the gap between socio-economic groups was observed.

Influence of Rest During Pregnancy on Birth Weight in Working Women

OBJECTIVE

Birth weight in Sweden has increased during the past decades. We investigated whether rest provided by the combination of time off from work and social benefits among working pregnant women contributed to the observed changes.

METHOD

A total of 7,459 consecutively delivered women in 1978, 1986, 1992, and 1997 at 2 delivery wards in southeastern Sweden were studied.

RESULTS

Between 1978 and 1997, the average birth weight among the children of the women studied increased from 3,484 to 3,566 grams (P < .001). The in-crease in weight was most evident among infants born to women who were employed during pregnancy. The use of social benefits and increased rest during pregnancy did not significantly influence birth weight (P = .107), even after adjustment for gestational length, parity, smoking, age, and occupation.

CONCLUSION

The continuous increase in infants' birth weight among pregnant women in this study did not correlate with rest periods in the form of leave supported by social benefit programs. The effects of social benefit programs on pregnancy outcome may thus be overrated and merits further research.

Why are the low birthweight rates in Brazil higher in richer than in poorer municipalities? Exploring the epidemiological paradox of low birthweight

Socio-economic disadvantage is usually associated with low birthweight (LBW). However, it has been shown that Mexican Americans, despite being economically less advantaged, present LBW rates that are similar to or lower than those found among white women in the US. This fact has been called 'the epidemiological paradox of low birthweight'. Natality data from Brazil revealed the existence of a similar paradox: LBW rates are higher in more developed than in less developed regions within the country. In this study, data from two population-based cohort studies carried out in the nineties, including 2439 births in Sao Luis, a poor city in north-eastern Brazil, and 2839 births in Ribeirao Preto, a socio-economically well-off city in south-eastern Brazil, were used to explore this paradox. The method proposed by Wilcox and Russell and a graphic analysis of the frequency distribution of birthweight according to gestational age were used to provide indirect information about possible gestational age misclassification. Contrary to expectations, the LBW rate was higher in Ribeirao Preto than in Sao Luis (10.7 vs. 7.6%, P <0.001), while preterm birth (PTB) rate (12.7 vs. 12.1%, P=0.520) and percentage of small-for-gestational-age (SGA) infants (12.5 vs. 13.5%, P=0.290) were similar for the two cities. However, SGA rate among preterm infants was higher in Ribeirao Preto (16.4 vs. 9.8%, P=0.014). A bimodal distribution of birthweight was observed for children with less than 32 weeks in Sao Luis. As estimated by the Wilcox and Russell method, the residual distribution was greater in Ribeirao Preto than in Sao Luis (3.4 vs. 2.4%). Part of the LBW paradox observed for the two cities was due to the higher PTB rate and higher number of preterm SGA infants in Ribeirao Preto. Factors such as greater medical intervention in preterm newborns close to the end of pregnancy in more developed municipalities, artefacts in the determination of gestational age, and the under-registration of livebirths and registration of livebirths as stillbirths in less developed municipalities may explain why LBW rates in Brazil are higher in richer than in poorer municipalities.

The impact of the increasing number of multiple births on the rates of preterm birth and low birthweight: an international study

OBJECTIVES

We studied the effects of twins and triplets on perinatal health indicators in the overall population in the 1980s and 1990s in Canada, England and Wales, France, and the United States.

METHODS

Data were derived mostly from live birth registration. We used rates, relative risks, and population attributable risks for twins and triplets separately.

RESULTS

In each country, the increase in multiple births, and the increase in preterm delivery among multiple births, contributed almost equally to the rise in or stabilization of the overall rates of preterm delivery. Twins contributed a much larger proportion of the preterm deliveries and low-birthweight newborns than did triplets.

CONCLUSIONS

Twins have a major population-based impact on the trends of perinatal health indicators.

Trends in the occurrence, determinants, and consequences of multiple births

After a substantial decrease in the middle of the 20th century, multiple pregnancy rates have increased in many Western countries. Between the mid-1970s and 1998, the rate of twin pregnancies increased by 50% to 60% in England and Wales, France, and the United States. The rates of triplet or higher-order multiple pregnancies increased by 310% in France, 430% in England and Wales, and 696% in the United States. One fourth to one third of the increase in twin or triplet pregnancies are attributable to a contemporaneous increase in maternal age. Furthermore, in countries with high occurrence of multiple births, 30% to 50% of twin pregnancies and at least 75% of triplet pregnancies occur after infertility treatment. The impact of the increase in multiple births on preterm delivery rates in the overall population is mainly attributable to twin pregnancies. In Canada, France, and the United States, an increase in preterm births among multiples contributed almost as much as the increase in occurrence of multiple births to the increase or stabilization of the overall rates of preterm delivery observed in these countries.

Trends and characteristics of induced labour in the United States, 1989-98

Induction of labour is one of the fastest growing medical procedures in the United States. In 1998, 19.2% of all US births were a product of induced labour, more than twice the 9.0% in 1989. Induction of labour has been efficacious in the management of post-term pregnancy and in expediting delivery when the mother or infant is sufficiently ill to make continuation of the pregnancy hazardous. However, the recent rapid increase in induction, and particularly the doubling of the induction rate for preterm pregnancies (from 6.7% in 1989 to 13.4% in 1998), has generated concern among some clinicians. The present study uses vital statistics natality data to examine the epidemiology of induced labour in the US. Multivariable analysis is used to examine the probability of having an induced delivery in relation to a wide variety of socio-demographic and medical characteristics, and also in relation to relative indications and contraindications for induced labour as outlined by the American College of Obstetricians and Gynecologists (ACOG). Induction rates were higher for women who were non-Hispanic white, college educated, born in the US, primaparae and those with intensive prenatal care utilisation. Induction rates were also higher for women with various medical conditions including hypertension, eclampsia and renal disease. For non-Hispanic white women with singleton births, 59% of the increase in the preterm birth rate from 1989 to 1998 can be accounted for by the increase in preterm inductions. The adjusted odds ratio for neonatal mortality among preterm births with induced labour was 1.20 [95% confidence interval 1.11, 1.31]. The rapid increase in induction rates, particularly among preterm births, marks a shift in the obstetric management of pregnancy. More detailed studies are needed to examine physician decision-making protocols, particularly for preterm induction, and to assess the impact of these practice changes on patient outcomes.

Risk factors for low birthweight in north-east Brazil: the role of caesarean section

Caesarean section (CS) delivery is associated with low birthweight (LBW) in south-east Brazil. A hospital-based study was conducted on singleton infants from mothers residing in São Luís, to assess if an association between CS and LBW was found in the northern part of the country, where the CS rate is lower than in the south-east. A standardised questionnaire was administered to a sample of 2541 mothers in 10 hospitals, representing 94% of all deliveries, from March 1997 to February 1998. In a logistic model, type of delivery was the independent variable, the other variables were treated as confounders, and interaction terms were added between type of delivery and all other factors. LBW was associated with low maternal height, maternal smoking, primiparity, previous LBW, public insurance, preterm birth and CS. The CS rate was 33.7%. The risk of CS was higher for primiparous and married mothers, those with high level of schooling and attended by the same physician during prenatal and delivery care, deliveries held in private hospitals, daylight hours or evenings, and for those mothers who had adequate prenatal care. Because it appears unlikely that only medical reasons are operative, it is a possibility that CS could cause LBW, reflecting abusive indications for elective CS.

Multiple deliveries in North Carolina: effects on birth outcomes

OBJECTIVES

The purpose of this study is to examine the trends in multiple deliveries in North Carolina and assess their effect on the rates of low birth weight, fetal mortality, and infant mortality.

METHODS

Using North Carolina vital statistics files, trends in multiple births, categorized by race, maternal age, and birth weight, were examined for the period 1980-1997. A partitioning method was used to estimate the contribution of maternal age distribution and age-specific multiple birth rates to the overall increase in multiple births, and the contribution of the changing multiple birth rate to observed trends in low birth weight and fetal and infant mortality.

RESULTS

Between 1980 and 1997, the state's multiple birth rate increased by 40%. Most of the increase was due to a rise in the age-specific multiple birth rates, rather than a shift in the maternal age distribution. The increase in the multiple birth rate accounted for a substantial proportion of the increase in low birth weight among Whites and Blacks. The rise in multiple births also hindered further declines in fetal and infant mortality during this time.

CONCLUSIONS

Multiple births are an increasingly important contributor to perinatal outcomes, and warrant greater consideration in research aimed at evaluating trends in low birth weight and infant mortality.