Investigating the Prevalence of Preterm Birth in Iranian Population: A Systematic Review and Meta-Analysis

Introduction: Despite medical advances, preterm delivery remains a global problem in developed and developing countries. The present study was aimed at conducting a systematic review and meta-analysis of studies on the prevalence of preterm delivery in Iran.

Methods: This study was carried out on studies conducted in Iran by searching databases of SID, Magiran, Irandoc, MEDLIB, Iranmedex, PubMed, Web of science, Google Scholar and Scopus. The search was conducted using advanced search and keywords of preterm delivery and equivalents of it in Mesh and their Farsi’s Synonymous in all articles from 2000-2016.After extracting the data, the data were combined using a random model. Heterogeneity of the studies was assessed using Q test I2 index and the data were analyzed using STATA Ver.11 software.

Results: The total number of samples in this study was 41773. In 19 reviewed articles, the overall prevalence of preterm delivery, based on the random effects model, was estimated to be a total of 10% (95% CI, 9-12). The lowest prevalence of preterm labor was 5.4% in Bam and the highest prevalence was 19.85% in Tehran. There was no significant difference between the prevalence of preterm delivery compared to year of study and sample size.

Conclusion: This study reviewed the findings of previous studies and showed that preterm delivery is a relatively prevalent problem in Iran. Therefore, adopting appropriate interventions in many cases including life skills training, self-care and increasing pregnancy care to reduce these consequences and their following complications in high risk patients seem necessary.

Gestational weight gain and preterm birth in obese women: a systematic review and meta-analysis

BACKGROUND

Prepregnant obesity is a global concern and gestational weight gain has been found to influence the risks of preterm birth.

OBJECTIVE

To assess the relationship between gestational weight gain and risk for preterm birth in obese women.

SEARCH STRATEGY

Four electronic databases were searched from 18 February through to 28 April 2015.

SELECTION CRITERIA

Primary research reporting preterm birth as an outcome in obese women and gestational weight gain as a variable that could be compared to the 2009 Institute of Medicine's recommendations.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed trials for inclusion. The Newcastle Ottawa Scale was used to assess study bias.

MAIN RESULTS

Our search identified six studies meeting the inclusion criteria; five were conducted in the USA and one in Peru. Four studies with a total of 10 171 obese women were meta-analysed. Significant heterogeneity was found between studies in the pooled analysis. Results for indicated preterm birth in obese women with gestational weight gain above the Institute of Medicine's recommendations showed increased risk (adjusted odds ratio 1.54; 95% CI 1.09-2.16).

CONCLUSIONS

Available science on this topic is limited to special populations of obese pregnant women. Generalisable research is needed to assess the variation in risk for preterm birth in obese women by differences in gestational weight gain and class of obesity controlling for significant variables in the pathway to preterm birth. This research has the potential to illuminate new science impacting preterm birth and interventions for prevention.

Folic acid supplementation, preconception body mass index, and preterm delivery: findings from the preconception cohort data in a Chinese rural population

BACKGROUND

Folic acid (FA) supplementation before and during the first trimester can reduce the risk of occurrence of preterm delivery (PTD). Preconception body mass index (BMI) is also associated with PTD. This study aimed to investigate the combined effect of FA supplements and preconception BMI on the risk of PTD.

METHODS

The data of a cohort from 2010-2011 that was obtained through a preconception care service in China was used (including 172,206 women). A multivariable regression model was used to investigate the association between maternal preconception conditions and the risk of PTD. The interaction of preconception BMI and FA supplementation was measured by a logistic regression model.

RESULTS

Taking FA supplements in the preconception period or in the first trimester reduced the risk of PTD (odds ratio [OR] = 0.58 and OR = 0.61, respectively). Women with an abnormal BMI had an increased risk of PTD (OR = 1.09, OR = 1.10, and OR = 1.17 for underweight, overweight, and obese, respectively). Preconception BMI showed an interaction with the protective effect of FA supplementation for PTD. With regard to the interaction of FA supplementation, the adjusted odds ratio (aOR) was 0.57 (95% CI: 0.51, 0.64) in underweight women, 0.85 (95% CI: 0.73, 0.98) in overweight women, and 0.77 (95% CI, 0.65, 0.91) in obese women. Preconception BMI also showed an interaction with the time of FA supplementation. Women with a normal BMI who began to take FA supplements in the preconception period had the lowest risk of PTD (aORs: 0.58 vs. 0.65 beginning in the first trimester). The aORs at preconception and the first trimester in the underweight group were 0.56 vs. 0.60. The aORs at preconception and the first trimester were 0.94 vs. 0.65 and 1.15 vs. 0.60 in the overweight and obesity groups, respectively.

CONCLUSIONS

In our study, FA supplements reduced the risk of PTD, while abnormal BMI raised the risk of PTD, although higher BMI categories did not have this higher risk once adjusted analysis was conducted. The protective effect of FA supplementation for PTD was reduced in women with overweight or obesity. To get better protection of FA supplementation, women with normal BMI or underweight should begin to use in preconception, while women with overweight or obesity should begin to use after conception.

Metabolic syndrome in preeclampsia women in gorgan

The aim of study was to assess the metabolic syndrome in preeclampsia women. The study was performed on 50 women. The metabolic syndrome prevalence was 66%. Serum glucose, triglyceride and LDL-cholesterol levels significantly were increased and HDL- cholesterol level significantly was decreased in metabolic syndrome patients. These patients showed high prevalence of components of the syndrome. Our results show the importance of dyslipidemia in preeclampsia in overweight and obese women. Preeclampsia and cardiovascular disease are important problems for the health of women. It may be useful to give a treat to people with a high-normal blood pressure in early pregnancy.

Preconception care: nutritional risks and interventions

INTRODUCTION

There is increasingly a double burden of under-nutrition and obesity in women of reproductive age. Preconception underweight or overweight, short stature and micronutrient deficiencies all contribute to excess maternal and fetal complications during pregnancy.

METHODS

A systematic review and meta-analysis of the evidence was conducted to ascertain the possible impact of preconception care for adolescents, women and couples of reproductive age on maternal, newborn and child health (MNCH) outcomes. A comprehensive strategy was used to search electronic reference libraries, and both observational and clinical controlled trials were included. Cross-referencing and a separate search strategy for each preconception risk and intervention ensured wider study capture.

RESULTS

Maternal pre-pregnancy weight is a significant factor in the preconception period with underweight contributing to a 32% higher risk of preterm birth, and obesity more than doubling the risk for preeclampsia, gestational diabetes. Overweight women are more likely to undergo a Cesarean delivery, and their newborns have higher chances of being born with a neural tube or congenital heart defect. Among nutrition-specific interventions, preconception folic acid supplementation has the strongest evidence of effect, preventing 69% of recurrent neural tube defects. Multiple micronutrient supplementation shows promise to reduce the rates of congenital anomalies and risk of preeclampsia. Although over 40% of women worldwide are anemic in the preconception period, only one study has shown a risk for low birth weight.

CONCLUSION

All women, but especially those who become pregnant in adolescence or have closely-spaced pregnancies (inter-pregnancy interval less than six months), require nutritional assessment and appropriate intervention in the preconception period with an emphasis on optimizing maternal body mass index and micronutrient reserves. Increasing coverage of nutrition-specific and nutrition-sensitive strategies (such as food fortification; integration of nutrition initiatives with other maternal and child health interventions; and community based platforms) is necessary among adolescent girls and women of reproductive age. The effectiveness of interventions will need to be simultaneously monitored, and form the basis for the development of improved delivery strategies and new nutritional interventions.

Preconception care: delivery strategies and packages for care

The notion of preconception care aims to target the existing risks before pregnancy, whereby resources may be used to improve reproductive health and optimize knowledge before conceiving. The preconception period provides an opportunity to intervene earlier to optimize the health of potential mothers (and fathers) and to prevent harmful exposures from affecting the developing fetus. These interventions include birth spacing and preventing teenage pregnancy, promotion of contraceptive use, optimization of weight and micronutrient status, prevention and management of infectious diseases, and screening for and managing chronic conditions. Given existing interventions and the need to organize services to optimize delivery of care in a logical and effective manner, interventions are frequently co-packaged or bundled together. This paper highlights packages of preconception interventions that can be combined and co-delivered to women through various delivery channels and provides a logical framework for development of such packages in varying contexts.

Urinary metabolic profiles in early pregnancy are associated with preterm birth and fetal growth restriction in the Rhea mother-child cohort study

BACKGROUND

Preterm birth (PB) and fetal growth restriction (FGR) convey the highest risk of perinatal mortality and morbidity, as well as increasing the chance of developing chronic disease in later life. Identifying early in pregnancy the unfavourable maternal conditions that can predict poor birth outcomes could help their prevention and management. Here we used an exploratory metabolic profiling approach (metabolomics) to investigate the association between birth outcomes and metabolites in maternal urine collected early in pregnancy as part of the prospective mother-child cohort Rhea study. Metabolomic techniques can simultaneously capture information about genotype and its interaction with the accumulated exposures experienced by an individual from their diet, environment, physical activity or disease (the exposome). As metabolic syndrome has previously been shown to be associated with PB in this cohort, we sought to gain further insight into PB-linked metabolic phenotypes and to define new predictive biomarkers.

METHODS

Our study was a case-control study nested within the Rhea cohort. Major metabolites (n = 34) in maternal urine samples collected at the end of the first trimester (n = 438) were measured using proton nuclear magnetic resonance spectroscopy. In addition to PB, we used FGR in weight and small for gestational age as study endpoints.

RESULTS

We observed significant associations between FGR and decreased urinary acetate (interquartile odds ratio (IOR) = 0.18 CI 0.04 to 0.60), formate (IOR = 0.24 CI 0.07 to 0.71), tyrosine (IOR = 0.27 CI 0.08 to 0.81) and trimethylamine (IOR = 0.14 CI 0.04 to 0.40) adjusting for maternal education, maternal age, parity, and smoking during pregnancy. These metabolites were inversely correlated with blood insulin. Women with clinically induced PB (IPB) had a significant increase in a glycoprotein N-acetyl resonance (IOR = 5.84 CI 1.44 to 39.50). This resonance was positively correlated with body mass index, and stratified analysis confirmed that N-acetyl glycoprotein and IPB were significantly associated in overweight and obese women only. Spontaneous PB cases were associated with elevated urinary lysine (IOR = 2.79 CI 1.20 to 6.98) and lower formate levels (IOR = 0.42 CI 0.19 to 0.94).

CONCLUSIONS

Urinary metabolites measured at the end of the first trimester are associated with increased risk of negative birth outcomes, and provide novel information about the possible mechanisms leading to adverse pregnancies in the Rhea cohort. This study emphasizes the potential of metabolic profiling of urine as a means to identify novel non-invasive biomarkers of PB and FGR risk.

The effect of impaired sleep on preterm labour

BACKGROUND

Sleep disturbance has become an important health problem for pregnant women. In fact, pregnancy-associated sleep disorder has been recognized as a distinct clinical entity. We aimed to study the relationship between sleep disturbance and preterm birth during pregnancy in a sample of Iranian women.

METHODS

In this analytical cohort study, 231 pregnant women in their 28th-32nd gestational week were recruited, using the multistage sampling method, from four healthcare centres in Ardabil, Iran, during 2010. The women were followed-up until 37-week gestation. One hundred and twelve women did not have sleep disturbances while 119 women had sleep disturbances. The Insomnia Severity Index (ISI), Epworth Sleepiness Scale (ESS), and a demographic data questionnaire were used for data collection. Data were analysed using SPSS software. Descriptive statistics, t, Chi-square, Fisher's exact, and Mann-Whitney tests were used as appropriate.

RESULTS

The prevalence of preterm labour was 11.8% in women with sleep disorder compared with 11.6% in women without sleep disorder (p = 0.9). Sleep duration less than eight hours, daytime dysfunction and impaired quality of life as a component of ISI showed a significant relationship with preterm birth (p = 0.02, p = 0.044, and p = 0.047, respectively).

CONCLUSION

Although daily dysfunction and lower quality of life because of sleep problems, and total sleep duration were variables associated with preterm birth, we found no significant relationship between sleep disorder and preterm birth.

Selected preconception health indicators and birth weight disparities in a national study

BACKGROUND

This analysis explored the effect of timing, sequencing, and change in preconception health across adolescence and young adulthood on racial/ethnic disparities in birth weight in a diverse national cohort of young adult women.

METHODS

Data came from Waves I (1994-1995), III (2001-2002), and IV (2007-2008) of the National Longitudinal Study of Adolescent Health. Eligibility was restricted to all singleton live births to female non-Hispanic White, non-Hispanic Black, Mexican-origin Latina, or Asian/Pacific Islander participants (n = 3,014) occurring between the Wave III (ages 18-26 years) and IV (ages 24-32 years) interviews. Birth weight was categorized into low (<2,500 g), normal (2,500-4,000 g), and macrosomic (>4,000 g). Preconception health indicators were cigarette smoking, heavy alcohol consumption, overweight or obesity, and inadequate physical activity, measured in adolescence (Wave I, ages 11-19 years) and early adulthood (Wave III) and combined into four-category variables to capture the timing and sequencing of exposure.

FINDINGS

Measures of preconception health did not explain the Black-White disparity in low birth weight, which increased after adjustment for confounders (odds ratio [OR], 2.17; 95% confidence interval [CI], 1.33-3.53) and effect modification by overweight/obesity (OR, 3.58; 95% CI, 1.65-7.78). A positive association between adult-onset overweight/obesity and macrosomia was modified by race (OR, 3.83; 95% CI, 1.02-14.36 for Black women).

CONCLUSIONS

This longitudinal analysis provides new evidence on preconception health and racial/ethnic disparities in birth weight. Specifically, it indicates that interventions focused on prevention of overweight/obesity and maintenance of healthy weight during the transition to adulthood, especially among Black females, may be warranted.

Autism spectrum disorder in children born preterm-role of exposure to perinatal inflammation

Autism Spectrum Disorder (ASD) is the collective term for neurodevelopmental disorders characterized by qualitative impairments in social interaction, communication, and a restricted range of activities and interests. Many countries, including Australia, have reported a dramatic increase in the number of diagnoses over the past three decades, with current prevalence of ASD at 1 in every 110 individuals (~1%). The potential role for an immune-mediated mechanism in ASD has been implicated by several studies, and some evidence suggests a potential link between prenatal infection-driven inflammation and subsequent development of ASD. Furthermore, a modest number of contemporary studies have reported a markedly increased prevalence of ASD in children born preterm, who are at highest risk of exposure to perinatal inflammation. However, the mechanisms that underpin the susceptibility to infection-driven inflammation during pregnancy and risk of preterm birth, and how these intersect with the subsequent development of ASD in the offspring, is not understood. This review aims to summarize and discuss the potential mechanisms and evidence for the role of prenatal infection on the central nervous system, and how it may increase the susceptibility for ASD pathogenesis in children born preterm.

Path analysis associations between perceived social support, stressful life events and other psychosocial risk factors during pregnancy and preterm delivery

BACKGROUND

Although several socio-medical risk factors have been identified for preterm labor, there is a gap in understanding the underlying etiology of preterm labor.

OBJECTIVES

The current study aimed to analyze the relationship pathway of perceived social support, stressful life events, and other psychosocial risk factors during pregnancy with incidence of preterm labor.

MATERIALS AND METHODS

In a prospective cohort study in four hospitals in Tehran, 500 pregnant women in their 24th to 28th gestational weeks were studied. They filled out a self-report questionnaire on perceived social support, depression, anxiety, stress and stressful life events. Sociodemographic characteristics were also assessed. The participants were followed up until labor, and the data about mother and the newborn were collected after labor. The data were analyzed by SPSS 16 and Lisrel 8.8 software programs using pathway analysis.

RESULTS

The final path model fit well (CFI = 0.96; RMSEA = .064). The results showed that depression, anxiety, and stress (β = -0.18) directly, and stressful life events indirectly (β= -0.0396) had the most predict on gestational age at labor. Perceived social support, directly through socioeconomic status (β=0.25), and indirectly through stress, depression and anxiety (β= -0.26) affected the gestational age at birth (β= 0.0468).

CONCLUSIONS

The current study showed that supporting pregnant mother moderates psychological problems such as stress, anxiety, and depression, and hence reduces preterm labor.

Pre-pregnancy BMI and weight gain: where is the tipping point for preterm birth?

BACKGROUND

Obesity in pregnant women is a major problem affecting both the mother and her offspring. Literature on the effect of obesity on preterm birth is inconsistent and few studies have investigated the influence of weight gain during pregnancy. This study examined the effect of maternal pre-pregnancy BMI and weight gain during pregnancy on preterm birth.

METHODS

Data from the Collaborative Perinatal Project (CPP) on 45,824 pregnant women with singleton, live-born infants with no sever congenital anomalies was analyzed. Primary outcome variables included preterm (< 37 weeks of gestation), categorized into spontaneous preterm with and without premature rupture of membrane (PROM) and indicated preterm. Maternal BMI was categorized into underweight (BMI < 18.50), normal weight (BMI =1 8.50 - 24.99), overweight (BMI = 25.00 - 29.99), and obese (BMI ≥ 30.00). Multinomial regression analysis was conducted and OR and 95% CI were calculated.

RESULTS

The rate of spontaneous preterm birth with PROM among overweight women decreased with increasing weight gain but increased among women who had excessive weight gain. Similarly, a U-shaped rate of spontaneous preterm birth with and without PROM was observed in obese women. Gaining less weight was protective of spontaneous preterm with and without PROM among overweight and obese women compared to normal weight women. Among underweight women, gaining < 7 kg or 9.5-12.7 kg was associated with increased odds of indicated preterm birth. Appreciable differences were also observed in the association between pre-pregnancy BMI, gestational weight gain and the subtypes of preterm births among African Americans and Caucasian Americans.

CONCLUSION

Reduced weight gain during pregnancy among overweight and obese women is associated with reduced spontaneous preterm birth with and without PROM. Health care professionals and public health workers should be aware of this risk and adhere to the 2009 IOM guideline that recommended reduced weight gain during pregnancy for obese and overweight women.

Preterm delivery and psycho-social determinants of health based on World Health Organization model in Iran: a narrative review

Background:

Preterm delivery is still the primary cause of mortality and morbidity in infants, which shows a problematic condition in the care of pregnant women all over the world. This review study describes prevalence and psycho - socio-demographic as well as obstetrical risk factors related to live preterm delivery (PTD) in the recent decade in Iran.

Methods:

A narrative review was performed in Persian and international databases including PubMed, SID, Google Scholar, Iran Medex, Magiran and Irandoc from 2001 to 2010 with following keywords: preterm delivery and pregnancy outcomes with (prevalence, socioeconomic condition, structural determinant, Intermediary determinants, Psychosocial factor, Behavioral factor and Maternal circumstance, Health system) All of article was reviewed then categorized based on WHO model.

Results:

Totally 52 article were reviewed and 35 articles were selected, of which 26 were cross-sectional or longitudinal, 9 were analytical (cohort or case-control). The prevalence rates of preterm delivery in different cities of Iran were reported between 5.6% in Quom to 39.4% in Kerman. The most common social factors in structural determinant were educational level of mother, and in intermediary determinants were Psychosocial factor (maternal anxiety and stress during pregnancy), Behavioral factor and Maternal circumstance (violation and trauma) and in Health system, lack of prenatal care.

Conclusion:

The prevalence rate of preterm delivery is a matter of concern. Since many psycho-social factors may affect on the condition and its high rate in poor communities might reveals a causal relationship among biological and psychosocial factors, performing etiological investigations is recommended.

Biopsychosocial risk factors for preterm birth and postpartum emotional well-being: a case-control study on Turkish women without chronic illnesses

AIMS AND OBJECTIVES

The study aimed to determine bio-psycho-social risk factors for preterm birth in a sample of Turkish women without chronic illnesses and evaluate their anxiety and depression in early postpartum period.

BACKGROUND

Preterm birth is a devastating event with long-term health and social implications. Studies have identified several risk factors; however, the contribution of these causes differs by ethnic groups.

DESIGN

This case-control study was conducted in a tertiary hospital in Istanbul over one year. In total, 149 preterm mothers were included in the case group and 150 term mothers who delivered in the same day with a case group woman were included in the control group. Chronic illnesses and anomalies were excluded.

METHOD

Data were gathered using a form that addressed risk factors for preterm birth. Multidimensional Scale of Perceived Social Support, Beck Depression Inventory and Spielberger's State-Trait Anxiety Inventory were administered within 24-72 hours after birth.

RESULTS

Logistic regression analysis revealed that partner's lower education (≤ 8 years), history of preterm birth, antenatal hospitalisation, genitourinary infection and irregular prenatal care were significant risk factors. Perceived social support from family and friends were significantly lower in preterm group. Preterm mothers experienced significantly more anxiety and depressive symptoms in early postpartum.

CONCLUSION

Many of the socio-economical and obstetric causes of preterm births were similar to other countries with higher preterm birth rates. Preterm births were associated with lower social support along with more anxiety and depressive symptoms in early postpartum.

RELEVANCE TO CLINICAL PRACTICE

Women who have established risk factors can be targeted for more intensive antenatal care for the prevention of preterm birth. Increased maternal anxiety and depression reveal the necessity of emotional support immediately after birth.

Relationships between pregnancy outcomes, biochemical markers and pre-pregnancy body mass index

Objective:

We examined the relationships between pre-pregnancy maternal body mass index (BMI), pregnancy outcomes and biochemical markers.

Design:

This study was conducted as a cross-sectional analysis.

Subjects:

Korean women in their second and third trimesters of pregnancy were recruited at two hospitals in the metropolitan Seoul area. Pre-pregnancy BMI was categorized in four groups according to the Asia-Pacific standard.

Measurements:

Fasting blood samples were obtained and analyzed for serum levels of homocysteine, folate and high-sensitivity C-reactive protein (hs-CRP). Concentrations of fetal fibronectin were assessed in the cervix and vagina, and cervical length was measured.

Results:

Obese subjects had a lower education level and a lower income level than subjects of normal weight. The level of maternal stress was positively associated with pre-pregnancy BMI. Normal weight subjects were more likely to eat breakfast and consume meals of appropriate size than the rest of our sample. In overweight and obese subjects, weight gain during pregnancy was significantly lower than in the underweight and normal subjects. High pre-pregnancy maternal BMI increased the risks of preterm delivery (odds ratio (OR)=2.85, confidence interval (CI)=1.20–6.74), low-birth-weight (LBW) infants (overweight subjects: OR=5.07, CI=1.76–14.63; obese subjects: OR=4.49, CI=1.54–13.13) and macrosomia. In obese subjects, the average serum folate level was significantly lower than in the underweight subjects. In obese subjects, the average serum hs-CRP level was significantly higher than in the rest of our sample.

Conclusion:

Pregnancy outcomes are influenced by pre-pregnancy BMI. These findings suggest that women can minimize their risks of preterm delivery, LBW and macrosomia by maintaining normal pre-pregnancy BMI.

Maternal obesity as a risk factor for very pre-term delivery in dichorionic twin pregnancies

We attempt here to identify the maternal characteristic factors most strongly associated with the increased risk of very pre-term delivery in dichorionic twin deliveries. Data were collected from 24 dichorionic twin pregnancies who were born at <32 weeks' gestation (very pre-term delivery) and 245 dichorionic twin pregnancies, who were born at 37-40 weeks' gestation as controls. Data included maternal age, height, body weight, body mass index (BMI), history of abortion, parity, maternal smoking, history of infertility therapy, such as in vitro fertilisation and/or embryo reduction, chronic hypertension and diabetes mellitus. Using logistic regression, the risk of very pre-term delivery was significantly increased among obese women (BMI >or=30 during prepregnancy; the adjusted odds ratio: 5.1, 95% confidence intervals: 1.2-21, p = 0.01). The current results indicate that maternal obesity is an independent risk factor for very pre-term delivery in dichorionic twin pregnancies.

Maternal obesity, associated complications and risk of prematurity

OBJECTIVE

We aimed at (a) examining the rates of obesity over a 12-year period; (b) studying the effect of obesity and morbid obesity on gestational age and birth weight and (c) determining the influence of race on the association between maternal obesity and the gestational age of a newborn.

STUDY DESIGN

We conducted a retrospective analysis using data from the perinatal data set of mothers delivering at the George Washington University between 1992 and 2003. We stratified mother/infant pairs (n=14 183) into three groups on the basis of maternal prepregnancy body mass index (BMI): not obese (BMI<30), obese (BMI 30 to 39) and morbidly obese (BMI> or =40). We identified all spontaneous and induced preterm deliveries in each group. Bivariate and multivariate analyses were conducted to control for significant differences between groups.

RESULT

We identified obesity in 1707 (12%) and morbid obesity in 415 (3%) of the mothers. Obesity and morbid obesity increased over time during the study period. In crude analysis, mothers with obesity and morbid obesity were more likely to deliver prematurely (16.7 and 20.3%, respectively) when compared with nonobese women (14.5%), and were also more likely to have other complications including smoking, anemia, hypertension, diabetes and cesarean delivery. When controlling for these complications in a logistic regression model, obesity and morbid obesity were not associated with prematurity.

CONCLUSION

There is no direct link between obesity and prematurity. Prematurity is more likely caused by medical complications that frequently occur in obese women. Further studies are needed on this growing population to test whether providing adequate prenatal care can control the associated medical conditions and subsequently ameliorate the rate of prematurity.

Obesity in older mothers, gestational weight gain, and risk estimates for preterm phenotypes

OBJECTIVE

To assess whether advanced maternal age modifies the relationship between maternal pregravid weight status, gestational weight gain patterns, and the occurrence of spontaneous preterm birth (SPB) and medically indicated preterm birth (MIPB).

METHODS

Retrospective cohort analysis of vital statistics data from the state of Florida for the period 2004 through 2007 comprising 311,422 singleton pregnancies (two age groups: 20-24 years old or younger women and >or=35 years or older women). Mothers were classified into five clusters based on their pre-pregnancy body mass index (BMI) values: non-obese (less than 30), class I obese (30.0<or=BMI<or=34.9), class II obese (35.0<or=BMI<or=39.9), class III obese (40<or=BMI<or=49.9), and super-obese (BMI>or=50.0).

RESULTS

MIPB occurred more frequently among older than younger women [11.8% vs. 6.4%, respectively (p<0.0001)) whereas SPB occurred more frequently among younger women [11.3% vs. 10.5%, respectively (p<0.0001)). Maternal obesity increased the risk for MIPB but not for SPB. Regardless of BMI status, the risk of MIPB was elevated among older mothers, particularly among those with suboptimal (<0.23 kg/week) and supraoptimal (>0.68 kg/week) gestational weight gain. A dose-response relationship with increasing gestational weight gain was evident (p<0.01); the greatest risk for MIPB occurred among older mothers with weekly gestational weight gain in excess of 0.79 kg (OR=7.76, 95% CI=5.73-10.5).

CONCLUSION

The occurrence of medically indicated preterm birth is positively associated with increased maternal pregravid body weight, older maternal age and extremes of gestational weight gain. Targeted pre- and inter-conception weight management efforts should be particularly encouraged in older mothers.

Metabolic syndrome in early pregnancy and risk of preterm birth

The authors determined the association between metabolic syndrome in early pregnancy (mean, 11.96 weeks) and the risk of preterm birth in the mother-child cohort study ("Rhea" Study) in Crete, Greece, 2007-2009. Maternal fasting serum samples were collected, and blood pressure was measured at the time of the first major ultrasound examination (n = 625). Multivariable log-binomial regression models were used. Women with metabolic syndrome were at high risk for preterm birth (relative risk (RR) = 2.93, 95% confidence interval (CI): 1.53, 5.58), with the highest risk observed for medically indicated preterm births (RR = 5.13, 95% CI: 1.97, 13.38). Among the components of metabolic syndrome, the most significant risk factor was hypertension (RR = 2.32, 95% CI: 1.28, 4.20). An elevation of 10 mm Hg in diastolic blood pressure increased the relative risk for preterm birth by 29% (RR = 1.29, 95% CI: 1.08, 1.53), while a per unit increase in the low density lipoprotein/high density lipoprotein cholesterol ratio increased this risk by 19% (RR = 1.19, 95% CI: 1.02, 1.39). Fetal weight growth restriction was associated with elevated levels of insulin (RR = 1.14, 95% CI: 1.08, 1.20) and diastolic blood pressure (RR = 1.27, 95% CI: 1.00, 1.61) in early pregnancy. These findings suggest that women with metabolic syndrome in early pregnancy had higher risk for preterm birth.