Assessing Weight Gain by the 2009 Institute of Medicine Guidelines and Perinatal Outcomes in Twin Pregnancy

Objective The objective is to estimate the impact of maternal weight gain outside the 2009 Institute of Medicine recommendations on perinatal outcomes in twin pregnancies. Study Design Twin pregnancies with two live births between January 1, 2004 and December 31, 2014 delivered after 23 weeks Finger Lakes Region Perinatal Data System (FLRPDS) and Central New York Region Perinatal Data System were included. Women were classified into three groups using pre-pregnancy body mass index (BMI). Perinatal outcomes in women with low or excessive weekly maternal weight gain were assessed using normal weekly weight gain as the referent in each BMI group. Results Low weight gain increased the risk of preterm delivery, birth weight less than the 10th percentile for one or both twins and decreased risk of macrosomia across all BMI groups. There was a decreased risk of hypertensive disorders in women with normal pre-pregnancy weight and an increased risk of gestational diabetes with low weight gain in obese women. Excessive weight gain increased the risk of hypertensive disorders and macrosomia across all BMI groups and decreased the risk of birth weight less than 10th percentile one twin in normal pre-pregnancy BMI group. Conclusion Among twin pregnancies, low weight gain is associated with low birth weight and preterm delivery in all BMI groups and increased risk of gestational diabetes in obese women. Our study did not reveal any benefit from excessive weekly weight gain with potential harm of an increase in risk of hypertensive disorders of pregnancy. Normal weight gain per 2009 IOM guidelines should be encouraged to improve pregnancy outcome in all pre-pregnancy BMI groups.     

Interpregnancy Interval and Risk of Adverse Pregnancy Outcomes: A Register-Based Study of 328,577 Pregnancies in Denmark 1994–2010

Objectives To investigate the associations of interpregnancy interval (IPI) with miscarriage, stillbirth, preterm delivery and small for gestational age delivery. Methods The study population comprised all women who had a live birth and at least one subsequent pregnancy in Denmark during the period from 1994 to 2010 (N?=?328,577). Linear regression was used to estimate risk differences for miscarriage, stillbirth, preterm delivery and small for gestational age delivery according to IPI. Results The results were heterogeneous: the risk of miscarriage increased monotonically with the length of the IPI. Compared to women with IPIs of 18–23 months, women with IPIs of 0–5 months experienced 18.7 (13.1–24.2) fewer miscarriages per 1000 pregnancies, while women with IPIs of ≥?60 months experienced 28.7 (23.4–34.0) more miscarriages per 1000 pregnancies. We found that women with IPIs of ≥?60 months had 1.7 (0.4–3.0) more stillbirths per 1000 births compared to women with IPIs of 18–23 months. U-shaped associations were seen for preterm delivery and small for gestational age delivery with women with IPIs of 18–23 months experiencing the lowest risks of these outcomes. Conclusions for Practice The heterogeneity in associations between IPI and adverse pregnancy outcomes suggests that different mechanisms of action may be at play at various times in the antepartum period. While the finding for miscarriage suggests that fecundity is an important determinant for IPI, the findings for preterm delivery and small for gestational age delivery suggest the coexistence of the maternal depletion syndrome mechanism and the physiological regression mechanism and the finding for stillbirth speaks against a strict maternal depletion syndrome explanation.     

Assessing the Risk of Having Small for Gestational Age Newborns Among Lebanese Underweight and Normal Pre-pregnancy Weight Women

Introduction It has been established that underweight women with low gestational weight gain (GWG) are at a higher risk of having Small for Gestational Age (SGA) newborns. However, the association remains poorly studied in Middle Eastern societies exhibiting different ethnic groups, genetic predisposing factors along with differences in nutritional food intake during pregnancy. The aim of this study is to assess the risk of having a SGA newborn among underweight and normal weight BMI women while studying the role of GWG in this association. Methods This is a retrospective cross-sectional study of 62,351 singleton pregnancies from the National Collaborative Perinatal Neonatal Network between 2001 and 2009 from 27 hospitals across Lebanon. Women who had underweight and normal pre-pregnancy BMI were included. Results A total of 8.6% newborns were SGA and 6.6% of women were underweight. Among women with normal and underweight pre-pregnancy BMI, 8.6 and 12.4% had SGA births respectively. Overall, the adjusted OR of having SGA newborns was significantly higher among underweight women (OR = 1.448; 95%CI = 1.287–1.630) compared to normal pre-pregnancy BMI. Below normal weight gain significantly increased the odds of SGA for both normal and underweight pre-pregnancy BMI women, with adjusted ORs of 1.535 (95% CI = 1.418–1.661) and 1.970 (95%CI = 1.515–2.560) respectively. Discussion Higher risks of SGA newborns in underweight and normal BMI women with low GWG were observed. In addition, normal weight gain couldn’t protect underweight women of having risk for SGA newborns. Hence, all pregnant women should be encouraged to maintain healthy BMI before pregnancy and attain adequate GWG.     

Higher Pre-pregnancy BMI and Excessive Gestational Weight Gain are Risk Factors for Rapid Weight Gain in Infants

Objective To describe the effects of maternal pre-pregnancy body mass index (BMI) and gestational weight gain (GWG) on infant anthropometrics at birth and 3 months and infant growth rates between birth and 3 months. Methods Body weight prior to and during pregnancy and infant weight and length at birth and 3 months were collected from 600 mother–infant pairs. Adherence to GWG was based on IOM recommendations. Age and sex specific z-scores were calculated for infant weight and length at birth and 3 months. Rapid postnatal growth was defined as a difference of >0.67 in weight-for-age z-score between birth and 3 months. Relationships between maternal and infant characteristics were analysed using multilinear regression. Results Most women (65%) had a normal pre-pregnancy BMI and 57% gained above GWG recommendations. Infants were 39.3?±?1.2 weeks and 3431?±?447.9 g at birth. At 3 months postpartum 60% were exclusively breast fed while 38% received breast milk and formula. Having a pre-pregnancy BMI >25 kg/m² was associated with higher z-scores for birth weight and weight-for-age at 3 months. Gaining above recommendations was associated with higher z-scores for birth weight, weight-for-age and BMI. Infants who experienced rapid postnatal growth had higher odds of being born to women who gained above recommendations. Conclusion for Practice Excessive GWG is associated with higher birth weight and rapid weight gain in infants. Interventions that optimize GWG should explore effects on total and rates of early infant growth.     

Effect of interpregnancy interval on adverse perinatal outcomes — a national study

Background

The interpregnancy interval (IPI) has been reported to influence the outcome of pregnancy and birth. We performed a national study in Israel to determine the impact of IPI on multiple adverse perinatal outcomes.

Study Design

This longitudinal cohort study used birth certificates of siblings born to the same biological mother, with at least one previous birth and a subsequent singleton pregnancy. Adverse pregnancy outcomes included preterm delivery, very preterm birth, small for gestational age (SGA), very SGA (VSGA), early neonatal death and major congenital malformations. Multivariate logistic regression was performed for each outcome.

Results

The study included 440,838 of a total of 846,845 reported live births in Israel over 5 years; excluded were primiparas (32%), multifetal births (4.9%) and those with incomplete data (10.9%). For IPIs shorter than 6 months, there were significantly increased risks for preterm birth (OR=1.23), SGA (OR=1.14), VSGA (OR=1.15), early neonatal death (OR=1.62) and congenital malformations (OR=1.14). Intervals of 60 months or longer had higher risks for preterm birth (OR=1.39) and VSGA (OR=1.16).

Conclusion

Optimal IPI recommendation of >11 months is an accessible and low-cost means to improve multiple adverse perinatal outcomes.     

Does Maternal Exposure to Secondhand Tobacco Smoke During Pregnancy Increase the Risk for Preterm or Small-for-Gestational Age Birth?

Introduction While associations between active smoking and various adverse birth outcomes (ABOs) have been reported in the literature, less is known about the impact of secondhand smoke (SHS) on many pregnancy outcomes. Methods We examined the relationship between maternal exposure to SHS during pregnancy and preterm (<?37 weeks gestation) and small-for-gestational age (SGA; assessed using sex-, race/ethnic-, and parity-specific growth curves) singleton births using non-smoking controls from the National Birth Defects Prevention Study (1997–2011). Multivariable logistic regression models for household, workplace/school, and combined SHS exposure—controlled for maternal education, race/ethnicity, pre-pregnancy body mass index, and high blood pressure—were used to estimate adjusted odds ratios (aORs) and 95% confidence intervals (CIs). Interaction was assessed for maternal folic acid supplementation, alcohol use, age at delivery, and infant sex. Results Infants of 8855 mothers were examined in the preterm birth analysis with 666 (7.5%) categorized as preterm, 574 moderately preterm (32–36 weeks), and 92 very preterm (<?32 weeks). For the SGA analysis, infants of 8684 mothers were examined with 670 (7.7%) categorized as SGA. The aORs for mothers reporting both household and workplace/school SHS were elevated for preterm (aOR 1.99; 95% CI 1.13–3.50) and moderately preterm birth (32–36 weeks) (aOR 2.17; 95% CI 1.22–3.88). No results for the SGA analysis achieved significance, nor was evidence of interaction evident. Conclusion The findings suggest an association between SHS from multiple exposure sources and preterm birth, but no evidence for association with SGA births. Continued study of SHS and ABOs is needed to best inform public health prevention programs.     

Maternal Obesity and Risk of Preterm Birth and Low Birthweight in Hawaii PRAMS, 2000–2011

Objective Maternal obesity is a risk factor for preterm birth, a leading cause of infant morbidity and mortality. Native Hawaiian and other Pacific Islanders (NHOPI) have high rates of poor birth outcomes. Despite the high rates of obesity in NHOPI in Hawaii, the association with preterm birth has not been examined in this population. Methods We performed a retrospective cohort study of 20,061 women using data collected by Hawaii’s Pregnancy Risk Assessment Monitoring System (PRAMS) from 2000 to 2011. We investigated the contribution of maternal age, pre-pregnancy BMI, gestational diabetes, hypertension, race, socioeconomic status, and smoking to our primary outcomes of preterm birth and low birthweight using multivariable logistic regression, stratified by NHOPI versus non-NHOPI race. Results Pre-pregnancy obesity was more common in NHOPI than non-NHOPI women (23.9 and 10.5%, respectively; p?<?0.01). Overall, the risk for preterm birth increased with maternal obesity (BMI?≥?30.0; aOR?=?1.24, 95% CI 1.06–1.45, p?<?0.01), compared with normal weight women. Among NHOPI women, the prevalence of preterm birth was elevated compared with non-NHOPI women although the prevalence of low birth weight was lower. After adjusting for confounders, risk for preterm birth and low birth weight were elevated in NHOPI women compared with White women. Maternal obesity did not significantly affect the risk of prematurity within the NHOPI group. Conclusions for Practice Our study demonstrates an association between maternal pre-pregnancy obesity and preterm deliveries in Hawaii. NHOPI have high rates of pre-pregnancy obesity as well as increased risk of both preterm delivery and low birthweight when compared to White women. Further data are needed to assess interactions between race, maternal health, and neonatal morbidity, and to identify ways to improve birth outcomes for minority populations in the state of Hawaii.     

Postpartum Contraception and Interpregnancy Intervals Among Adolescent Mothers Accessing Public Services in California

Objective To determine the association of age at index birth with postpartum contraceptive use and optimal interpregnancy interval (IPI, defined as delivery to next pregnancy >18 months), controlling for provider type and client demographics among adolescent mothers who have repeat pregnancies. Methods California’s 2008 birth records were linked to California’s Medi-Cal and Family PACT claims data to identify 26,393 women with repeat births between 2002 and 2008, whose index birth occurred as an adolescent, and who received publicly-funded services within 18 months after the index birth. Multivariable regression analyses were conducted to examine the relationship between timing of contraception provision and interpregnancy intervals, adjusting for socio-demographic factors. Results Seventy-eight percent of adolescent women did not receive contraception at their first postpartum visit, and twenty-eight percent of adolescent women never received contraception from a Family PACT or Medi-Cal provider. Adolescents who were older at their index birth had lower rates of optimal IPIs. Native American, Asian-Pacific Islander and Latina women had lower rates of optimal IPIs compared to white women. Compared to those using only barrier methods, adolescent women receiving highly effective contraceptive methods had a 4.25 times higher odds of having an optimal IPI than those receiving hormonal methods (OR 2.10), or using no method (OR 0.70). Conclusion Effective postpartum contraceptive use and being a Family PACT provider were associated with optimal birth spacing among adolescent mothers, yet racial and ethnic disparities persisted. A missed opportunity was the provision of contraception at the first postpartum visit. Providers should aim to remove barriers to initiation of contraception at this visit.     

Is International or Asian Criteria-based Body Mass Index Associated with Maternal Anaemia,Low Birthweight,and Preterm Births among Thai Population?—An Observational Study

An observational study was conducted in the four southernmost provinces of Thailand aiming at determining the effect of international or Asian criteria-based body mass index (BMI) in predicting maternal anaemia, low birthweight (LBW), and preterm births among pregnant Thai women and the change in haemoglobin (Hb) level during pregnancy. Maternal anaemia was defined as a haemoglobin (Hb) level of <11 g/dL. Anaemia was detected in 27.4% and 26.9% of 1,192 pregnant women at their first prenatal visit and the third trimester respectively. The proportions of overweight and obese women according to the Asian criteria-based pre-pregnancy BMI were higher than the international criteria-based BMI (22.4% and 10.1% vs 15.5% and 3.4% respectively). No significant difference between pre-pregnancy BMI and pregnancy BMI at the first prenatal visit was demonstrated (mean±standard deviation=21.8±4.0 vs 22.8±4.1). Underweight women had a significantly higher prevalence of maternal anaemia, LBW, and preterm birth compared to women with normal weight. Overweight and obese women at pre-pregnancy by the Asian criteria-based BMI had a lower prevalence of anaemia. The Hb levels did not change significantly over time. In addition to BMI, maternal age, parity, and late prenatal visit were independently associated with maternal anaemia, low birthweight, and preterm birth. Underweight pregnant women classified by international or Asian criteria-based BMI increased the risk of maternal anaemia, low birthweight, and preterm birth.Key words: Anaemia, Body mass index, Observational studies, Pregnancy, Thailand     

The Independent Importance of Pre-pregnancy Weight and Gestational Weight Gain for the Prevention of Large-for Gestational Age Brazilian Newborns

Objectives To study the independent effect of pre-pregnancy weight, gestational weight gain (GWG), and other important risk factors on newborn birth weight. Methods Baseline data of 435 adult women and their singletons born between January and February 2012 at a public hospital in Brazil were used. Logistic regression was applied to determine the independent importance of pre-pregnancy weight and GWG for large for gestational age (LGA) newborns. Results Among all mothers, 37.9 % were overweight and obese before pregnancy and 45.3 % experienced excessive GWG. Among the newborns, 24.4 % were classified as LGA. Univariate analysis showed an association of family income, GWG, pre-pregnancy BMI and excessive GWG with LGA newborns. Smoking before and during pregnancy was associated with a decreased likelihood of giving birth to an LGA newborn compared to mothers who did not smoke. After adjustment for confounding variables, age at birth of first child, GWG, HbA1c and pre-pregnancy weight-GWG were significant and independent determinants of giving birth to an LGA newborn. Mothers with pre-pregnancy overweight and excessive GWG were more likely to deliver an LGA newborn (OR 2.54, P < 0.05) compared to mothers who were normal weight and experienced adequate GWG. Conclusions for Practice Age at first birth of child, GWG, HbA1c and pre-pregnancy overweight combined with excessive GWG are independent determinants of LGA newborns. The results of this study suggest that both primary prevention of overweight in women of childbearing age and management of GWG may be important strategies to reduce the number of LGA newborns and, consequently, the long-term public health burden of obesity.     

Comparison of Self-reported and Measured Pre-pregnancy Weight: Implications for Gestational Weight Gain Counseling

Objectives To examine clinical and demographic characteristics associated with availability of self-reported and measured pre-pregnancy weight, differences in these parameters, and characteristics associated with self-report accuracy. Methods Retrospective cohort of 7483 women who delivered at a large academic medical center between 2011 and 2014. Measured pre-pregnancy weights recorded within a year of conception and self-reported pre-pregnancy weights reported anytime during pregnancy were abstracted from electronic medical records. Difference in weights was calculated as self-reported minus measured pre-pregnancy weight. Logistic and linear regression models estimated associations between demographic and clinical characteristics, and presence of self-reported and measured weights, and weight differences. Results 42.2% of women had both self-reported and measured pre-pregnancy weight, 49.7% had only self-reported, and 2.8% had only measured. Compared to white women, black women and women of other races/ethnicities were less likely to have self-reported weight, and black, Asian, and Hispanic women, and women of other races/ethnicities were less likely to have measured weights. For 85%, pre-pregnancy BMI categorized by self-reported and measured weights were concordant. Primiparas and multiparas were more likely to underreport their weight compared to nulliparas (b?=??1.32 lbs, 95% CI ?2.24 to ?0.41 lbs and b?=??2.74 lbs, 95% CI ?3.82 to ?1.67 lbs, respectively). Discussion Utilization of self-reported or measured pre-pregnancy weight for pre-pregnancy BMI classification results in identical categorization for the majority of women. Providers may wish to account for underreporting for patients with a BMI close to category cutoff by recommending a range of gestational weight gain that falls within recommendations for both categories where feasible.     

Deployment and Adverse Pregnancy Outcomes: Primary Findings and Methodological Considerations

Objective To characterize the pregnancy outcomes of women Operation Enduring Freedom/Operation Iraqi Freedom (OEF/OIF) Veterans including prevalence of preterm delivery, low birth weight, and macrosomia, and to highlight methodological limitations that can impact findings. Methods A retrospective cohort study was conducted starting in 2014 analyzing data from the 2009 to 2011 National Health Study for a New Generation of US Veterans, which sampled Veterans deployed and not deployed to OIF/OEF. All pregnancies resulting in a live birth were included, and categorized as occurring among non-deployers, before deployment, during deployment, or after deployment. Outcomes included preterm birth, low birth weight, and macrosomia. The association of deployment with selected outcomes was estimated using separate general estimating equations to account for lack of outcome independence among women contributing multiple pregnancies. Adjustment variables included maternal age at outcome, and race/ethnicity. Results There were 2276 live births (191 preterm births, 153 low birth weight infants, and 272 macrosomic infants). Compared with pregnancies before deployment, pregnancies among non-deployers and those after deployment appeared to have greater risk of preterm birth [non-deployers: odds ratio (OR) = 2.16, 95 % confidence interval (CI) 1.25, 3.72; after deployment: OR = 1.90, 95 % CI 0.90, 4.02]. A similar pattern was observed for low birth weight. No association of deployment with macrosomia was detected. Discussion Compared with non-deployers, those who eventually deploy appear to have better pregnancy outcomes prior to deployment, but this advantage is no longer apparent after deployment. Non-deployers may not be an appropriate reference group to study the putative health impacts of deployment on pregnancy outcomes.     

Examining the Prevalence Rates of Preexisting Maternal Medical Conditions and Pregnancy Complications by Source: Evidence to Inform Maternal and Child Research

Objectives We sought to examine whether there are systematic differences in ascertainment of preexisting maternal medical conditions and pregnancy complications from three common data sources used in epidemiologic research. Methods Diabetes mellitus, chronic hypertension, gestational diabetes mellitus (GDM), gestational hypertensive disorders (GHD), placental abruption and premature rupture of membranes (PROM) among 4821 pregnancies were identified via birth certificates, maternal self-report at approximately 4 months postpartum and by discharge codes from the Statewide Planning and Research Cooperative System (SPARCS), a mandatory New York State hospital reporting system. The kappa statistic (k) was estimated to ascertain beyond chance agreement of outcomes between birth certificates with either maternal self-report or SPARCS. Results GHD was under-ascertained on birth certificates (5.7?%) and more frequently indicated by maternal report (11?%) and discharge data (8.2?%). PROM was indicated more on birth certificates (7.4?%) than maternal report (4.5?%) or discharge data (5.7?%). Confirmation across data sources for some outcomes varied by maternal age, race/ethnicity, prenatal care utilization, preterm delivery, parity, mode of delivery, infant sex, use of infertility treatment and for multiple births. Agreement between maternal report and discharge data with birth certificates was generally poor (kappa?<?0.4) to moderate (0.4?≤?kappa?<?0.75) but was excellent between discharge data and birth certificates for GDM among women who underwent infertility treatment (kappa?=?0.79, 95?% CI 0.74, 0.85). Conclusions for Practice Prevalence and agreement of conditions varied across sources. Condition-specific variations in reporting should be considered when designing studies that investigate associations between preexisting maternal medical and pregnancy-related conditions with health outcomes over the life-course.     

The Impact of Prior Poor Birth Outcomes on Smoking Behavior on Subsequent Pregnancies: Analysis of the National PRAMS Data

Objectives The link between cigarette smoking and poor birth outcomes has been well established. However, there is paucity of research investigating the effect of previous history of poor birth outcomes on smoking behavior during subsequent pregnancies. The present study seeks to determine whether a previous preterm or low birth weight delivery impacts maternal smoking during the subsequent pregnancy. Methods Data from the National Pregnancy Risk Assessment Monitoring System (PRAMS) was analyzed. Multiparous women who currently had singleton birth were included in the analysis (N = 137,297). Previous poor birth outcome and smoking were defined based on the PRAMS question that asked women whether their immediate previous baby was born preterm or low birth weight and if they smoked during the index pregnancy. Results Approximately 16.3 % of the women who reported previous poor birth outcome also reported smoking during the subsequent pregnancy. Multiple logistic regression analysis revealed that women who had previous poor birth outcome had 22 % higher odds of smoking during the subsequent pregnancy. Similarly, the odds of smoking during pregnancy were 30 and 13 % higher among women who had previous low birth weight and preterm birth, respectively. Conclusions Women who experienced previous preterm or low birth weight baby had higher prevalence of smoking during the subsequent pregnancy. The occurrence of a preterm/low birth weight may present a critical intervention point for providers to educate women on the risks of repeated poor birth outcomes and provide intervention programs to address high-risk behaviors.     

Relationship Between Common Mental Disorder Symptoms During Pregnancy and Preterm Birth Among Chinese Women in Wuhan

Objectives Few studies focus on the symptoms of common mental disorders during pregnancy (CMDP) and risk of preterm birth subtypes (PTB). The purpose of this study was to estimate the association between CMDP and PTB, and to examine whether or not the association between CMDP and PTB varies with the subtype of PTB in Chinese. Methods This population-based case control study, conducted in Wuhan, China, defined cases as every pregnant woman who had a PTB among all births in Wuhan, from June 10, 2011, to June 9, 2013. The same number of pregnant women who had term births was randomly selected as controls. The Electronic Perinatal Health Care Information System, a questionnaire designed for the study, provided data about the participants. Logistic regression analyses were used to model associations betweenCMDP and PTB, and to test associations between CMDP and two subtypes of PTB. Results The study recruited 8616 cases and an equal number of controls. We successfully collected maternal information on 6656 cases and controls for a response rate of 77.3 %. The incidence of PTB in Wuhan was 4.5 %. Spontaneous preterm births (SPTB) accounted for 60.1 %, and medically induced preterm births (IPTB) accounted for 39.9 % of preterm births. The prevalence rate of CMDP was 15.8 %. CMDP was slightly associated with PTB (crude OR 1.16, 95 % CI 1.01–1.32; adjusted OR 1.15, 95 % CI 1.00–1.32), further analyses showed CMDP was associated with IPTB (aOR 1.25, 95 % CI 1.04–1.50), but not with SPTB. Conclusion Our data suggest that CMDP is related to an increased risk of PTB, and that this association is primarily due to IPTB rather than SPTB.     

舟山市2002-2015年出生体重变化与不良出生结局及影响因素分析

目的 描述舟山市2002-2015年新生儿出生体重变化,分析不良出生结局的发生率及影响因素。方法 利用舟山市电子医疗数据库,收集孕产妇及新生儿的相关信息,描述新生儿出生体重和不良出生结局发生率的变化趋势,采用多元Logistic回归分析其影响因素。结果 37 141例新生儿的平均出生体重为（3 388±462） g,低出生体重儿、巨大儿、早产的发生率分别为2.34%,9.42%和3.61%;高危妊娠（OR=1.80,95%CI:1.42~2.28）是低出生体重儿的危险因素;出生季节为夏季、秋季、母亲年龄<25岁、孕前消瘦等是巨大儿的保护因素。母亲孕前超重和肥胖是巨大儿的危险因素;母亲年龄<25岁是早产发生的保护因素。母亲年龄>30岁（OR=1.38,95%CI:1.19~1.60）、冬季出生（OR=1.24,95%CI:1.06~1.45）、母亲孕前超重和肥胖、高危妊娠（OR=1.95,95%CI:1.66~2.29）等是早产的危险因素。结论 舟山市2002-2015年新生儿出生体重呈下降趋势,低出生体重儿和早产儿发生率呈上升趋势。新生儿性别、出生季节,母亲年龄、孕前体质指数（body mass index,BMI）、高危妊娠等因素影响低出生体重儿、巨大儿或早产儿的发生。     

Hospital Utilization and Costs Among Preterm Infants by Payer: Nationwide Inpatient Sample, 2009

Objectives To describe hospital utilization and costs associated with preterm or low birth weight births (preterm/LBW) by payer prior to implementation of the Affordable Care Act and to identify areas for improvement in the quality of care received among preterm/LBW infants. Methods Hospital utilization—defined as mean length of stay (LOS, days), secondary diagnoses for birth hospitalizations, primary diagnoses for rehospitalizations, and transfer status—and costs were described among preterm/LBW infants using the 2009 Nationwide Inpatient Sample. Results Approximately 9.1 % of included hospitalizations (n = 4,167,900) were births among preterm/LBW infants; however, these birth hospitalizations accounted for 43.4 % of total costs. Rehospitalizations of all infants occurred at a rate of 5.9 % overall, but accounted for 22.6 % of total costs. This pattern was observed across all payer types. The prevalence of rehospitalizations was nearly twice as high among preterm/LBW infants covered by Medicaid (7.6 %) compared to commercially-insured infants (4.3 %). Neonatal transfers were more common among preterm/LBW infants whose deliveries and hospitalizations were covered by Medicaid (7.3 %) versus commercial insurance (6.5 %). Uninsured/self-pay preterm and LBW infants died in-hospital during the first year of life at a rate of 91 per 1000 discharges—nearly three times higher than preterm and LBW infants covered by either Medicaid (37 per 1000) or commercial insurance (32 per 1000). Conclusions When comparing preterm/LBW infants whose births were covered by Medicaid and commercial insurance, there were few differences in length of hospital stays and costs. However, opportunities for improvement within Medicaid and CHIP exist with regard to reducing rehospitalizations and neonatal transfers.     

Prepregnancy Obesity and Birth Outcomes

Objective To investigate the association between prepregnancy obesity and birth outcomes using fixed effect models comparing siblings from the same mother. Methods A total of 7496 births to 3990 mothers from the National Longitudinal Survey of Youth 1979 survey are examined. Outcomes include macrosomia, gestational length, incidence of low birthweight, preterm birth, large and small for gestational age (LGA, SGA), c-section, infant doctor visits, mother’s and infant’s days in hospital post-partum, whether the mother breastfed, and duration of breastfeeding. Association of outcomes with maternal pre-pregnancy obesity was examined using Ordinary Least Squares (OLS) regression to compare across mothers and fixed effects to compare within families. Results In fixed effect models we find no statistically significant association between most outcomes and prepregnancy obesity with the exception of LGA, SGA, low birth weight, and preterm birth. We find that prepregnancy obesity is associated with a with lower risk of low birthweight, SGA, and preterm birth but controlling for prepregnancy obesity, increases in GWG lead to increased risk of LGA. Conclusions Contrary to previous studies, which have found that maternal obesity increases the risk of c-section, macrosomia, and LGA, while decreasing the probability of breastfeeding, our sibling comparison models reveal no such association. In fact, our results suggest a protective effect of obesity in that women who are obese prepregnancy have longer gestation lengths, and are less likely to give birth to a preterm or low birthweight infant.     

The Association of Maternal Pre-pregnancy Body Mass Index with Breastfeeding Initiation

Recent evidence extends the health benefits of breastfeeding to include reduction of maternal body mass index (BMI) and childhood obesity. Since most women decide if they will breastfeed prior to pregnancy, it is important to understand, given the high population prevalence of obesity, if maternal underweight, overweight or obese status is associated with breastfeeding initiation. Population-based study. Florida resident birth certificate records. All live singleton births (2004–2009), excluding observations that lacked the primary outcomes of maternal pre-pregnancy BMI and breastfeeding initiation (final sample of 1,161,949 unique observations). Odds of initiating breastfeeding, adjusted by maternal and infant factors, stratified by pre-pregnancy BMI, categorized as underweight, normal, overweight and obese. Adjusting for the known maternal factors associated with breastfeeding initiation, underweight and obese women were significantly less likely to initiate breastfeeding than women with normal BMI, (adjusted odds ratio 0.87, 95 % confidence interval 0.85–0.89 for underweight women; 0.84, 95 % CI 0.83–0.85 for obese women). The magnitude of these findings did not significantly vary by race or ethnicity. Medicaid status and adherence to the Institute of Medicine’s 2009 pregnancy weight gain recommendations had only minor influences on breastfeeding initiation. Among adolescents, only underweight status predicted breastfeeding initiation; obesity did not. Underweight and obese women have significantly lower rates of breastfeeding initiation compared to women with normal pre-pregnancy BMI. Future studies need to address the health care, social, and physical barriers that interfere with breastfeeding initiation, especially in underweight and obese women, regardless of race, ethnicity or income.     

孕前体质指数、孕期增重与婴幼儿血红蛋白的关系

目的 探讨孕前体质指数（body mass index,BMI）、孕期增重与婴幼儿血红蛋白的关系。方法 选择按期体检与分娩的孕妇及婴儿作为研究对象,孕妇一般情况及分娩情况将由问卷调查的方式收集。并采用单因素分析和多因素Logistic回归模型进行数据分析。结果 受检对象共980例,按孕前BMI分组,孕前消瘦者占19.0%,孕前体重正常者占71.0%,孕前超重肥胖者占10.0%。孕期增重按美国国家科学院（institute of medicine,IOM）标准分组,孕期增重低于IOM推荐标准者占27.8%,符合IOM推荐标准者占31.4%,高于IOM推荐标准者占40.8%。贫血发生率为49.7%。单因素分析中孕前BMI、孕期增重对贫血均有统计学意义（均有P<0.05）。同时多因素分析显示,孕前消瘦者（OR=2.027,95%CI:1.433～2.867）,孕期增重不足者（OR=2.499,95%CI:1.772～3.523）是婴幼儿贫血的危险因素。结论 孕前BMI、孕期增重情况可能是婴幼儿贫血的危险因素,控制孕前BMI、孕期增重情况可以有效降低贫血的发生风险。