Macrosomic births in the united states: determinants, outcomes, and proposed grades of risk

Gestational Weight Gain and Adverse Neonatal Outcome Among Term Infants

OBJECTIVE

To examine the relationship between gestational weight gain and adverse neonatal outcomes among infants born at term (37 weeks or more).

METHODS

This was a retrospective cohort study of 20,465 nondiabetic, term, singleton births. We performed univariable and multivariable analyses of the associations between gestational weight gain and neonatal outcomes. We categorized gestational weight gain by the Institute of Medicine guidelines as well as extremes of gestational weight gain (less than 7 kg and more than 18 kg).

RESULTS

Gestational weight gain above the Institute of Medicine guidelines was more common than gestational weight gain below (43.3% compared with 20.1%). In multivariable analyses, gestational weight gain above guidelines was associated with a low 5-minute Apgar score (adjusted odds ratio [AOR] 1.33, 95% confidence interval [CI] 1.01-1.76), seizure (AOR 6.50, 95% CI 1.43-29.65), hypoglycemia (AOR 1.52, 95% CI 1.06-2.16), polycythemia (AOR 1.44, 95% CI 1.06-1.94), meconium aspiration syndrome (AOR 1.79, 95% CI 1.12-2.86), and large for gestational age (AOR 1.98, 95% CI 1.74-2.25) compared with women within weight gain guidelines. Gestational weight gain below guidelines was associated with decreased odds of neonatal intensive care unit admission (AOR 0.66, 95% CI 0.46-0.96) and increased odds of small for gestational age (SGA; AOR 1.66, 95% CI 1.44-1.92). Gestational weight gain less than 7 kg was associated with increased risk of seizure, hospital stay more than 5 days, and SGA. Gestational weight gain more than 18 kg was associated with assisted ventilation, seizure, hypoglycemia, polycythemia, meconium aspiration syndrome, and large for gestational age.

CONCLUSION

Gestational weight gain above guidelines was common and associated with multiple adverse neonatal outcomes, whereas gestational weight gain below guidelines was only associated with SGA status. Public health efforts among similar populations should emphasize prevention of excessive gestational weight gain.

Birth weight, maternal weight and childhood leukaemia

There is mounting evidence that childhood leukaemia is associated with high birth weight, but few studies have examined the relationship between leukaemia and other perinatal factors that influence birth weight, such as maternal weight or gestational weight gain. This case-cohort study included 916 acute lymphocytic leukaemia (ALL) and 154 acute myeloid leukaemia (AML) cases diagnosed prior to age 10 years between 1985 and 2001 and born in New York State excluding New York City between 1978 and 2001. Controls (n=9686) were selected from the birth cohorts for the same years. Moderate increased risk of both ALL and AML was associated with birth weight 3500 g or more. For ALL, however, there was evidence of effect modification with birth weight and maternal prepregnancy weight. High birth weight was associated with ALL only when the mother was not overweight while heavier maternal weight was associated with ALL only when the infant was not high birth weight. Increased pregnancy-related weight gain was associated with ALL. For AML, birth weight under 3000 g and higher prepregnancy weight were both associated with increased risk. These findings suggest childhood leukaemia may be related to factors influencing abnormal fetal growth patterns.

Fetal Macrosomia – A Continuing Obstetric Challenge

BACKGROUND

Macrosomic fetuses represent a continuing challenge in obstetrics.

OBJECTIVES

We studied maternal risk factors of fetal macrosomia and maternal and infant outcome in such cases.

METHODS

A retrospective cohort study was carried out with a total of 26,961 singleton pregnancies between 1989 and 2001. Records of 886 mothers who gave birth to live born infants weighing > or =4,500 g were compared to those of 26,075 mothers with normal weight (<4,500 g) infants. Multiple regression analysis was used to identify independent reproductive risk factors. Perinatal complications were also assessed.

RESULTS

The incidence of fetal macrosomia was 3.4%. Diabetes, previous macrosomic birth, postdatism (>42 weeks of gestation), obesity (BMI > 25 before pregnancy), male infant, gestational diabetes mellitus, and non-smoking were independent risk factors of fetal macrosomia, with adjusted risks of 4.6, 3.1, 3.1, 2.0, 1.9, 1.6, 1.4, respectively. In the macrosomic group, birth and maternal traumas occurred significantly more often than in the control group. However, records of subsequent pregnancies (n = 250) after the study period showed that a previous uncomplicated birth appeared to decrease complication risks.

CONCLUSIONS

Most cases of fetal macrosomia occur in low-risk pregnancies and evaluation of maternal risks cannot accurately predict which women will eventually give birth to an overweight newborn. After an uncomplicated birth of a macrosomic infant, vaginal delivery may be a safe option for the infant and mother.

[Use of continuous subcutaneous insulin infusion by a portable insulin pump during pregnancy in women with type 1 diabetes mellitus]

BACKGROUND/AIM

Diabetes mellitus is associated with an increased risk for neonatal morbidity and mortality. One of the most important goals in treating pregnancies complicated with diabetes is keeping glucose level within the normal range, especially in the first trimester. A portable insulin pump for continuous subcutaneous insulin infusion (CSII) represents the best form of therapy for patients with type 1 diabetes mellitus during pregnancy. The aim of our study was to evaluate the effects of therapy with a portable insulin pump for continuous subcutaneous insulin infusion during the first trimester of pregnancy on the quality of glycoregulation and pregnancy outcome in women with type 1 diabetes mellitus.

METHODS

A total of 17 newly diagnosed pregnant women with type 1 diabetes mellitus were treated with CSII therapy for three months. The parameters of glycoregulation (hemoglobin A, glycosylated--HbAlc, mean blood glucose value in daily profiles--MBG, daily requirement for insulin--IJ/kg BM), lipid levels, blood preassure and renal function were estimated before and after the therapy. These parameters were correlated with parameters of pregnancy outcome: fetal weight, APGAR score, duration of pregnancy.

RESULTS

There was a significant improvement in HbA1c (8.94 +/- 1.62 vs. 6.90 +/- 1.22 %,p < 0.05), MBG (9.23 +/- 2.22 vs. 6.41 +/- 1.72 mmol/l, p < 0.01), and daily requirement for insulin (0.66 +/- 0.22 vs. 0.55 +/- 0.13 IJ/kg BM, p < 0.05) during the CSII therapy. There were significant correlations between fetal weight and HbAlc (r = -0.60, p < 0.05), triglyceride levels (r = -0.63, p < 0.01), and the number of pregnancies (r = -0.62, p < 0.01), as well as between APGAR score and MBG (r = -0.52, p < 0.05) and cholesterol levels (r = -0.65, p < 0,01) before a portable insulin pump was applicated.

CONCLUSIONS

There was a significant improvement in the quality of glycoregulation during CSII therapy in the pregnant women with type 1 diabetes mellitus. The quality of glycoregulation in the moment of conception was the important factor for pregnancy outcome.

Secular change in size at birth from 1973 to 2003: national data from Denmark

OBJECTIVE

To explore whether birth weight (BW) has been increasing in Denmark at the same level as in other countries and whether this increase is paralleled by an increase in birth length (BL) or whether body proportionality, expressed as ponderal index (PI), has changed.

RESEARCH METHODS AND PROCEDURES

This study used data analysis of information from The Danish Medical Birth Registry including all single live births in Denmark from 1973 to 2003 (n = 1,863,456). BW, BL, gestational age, maternal age, and smoking status (only from 1991 on) were measured.

RESULTS

Mean BW increased steadily during the period (160 grams; equivalent to approximately 5 g/yr) at a rate higher than that reported from other countries. BL showed only a minor increase (2.4 mm), leading to an increase in PI (0.8 kg/m3) during the period. Controlling for the effect of increasing maternal age and decreasing gestational age and maternal smoking prevalence (only data after 1991), there was still an increase in BW of approximately 4 g/yr.

DISCUSSION

During the last 30 years, neonates have become bigger, with a larger relative increase in BW than BL, leading to an increase in PI. The increasing BW and PI, which may be caused by increased maternal weight, could further promote the obesity epidemic.

Pregnancy outcomes of First Nations women in relation to pregravid weight and pregnancy weight gain

OBJECTIVE

To determine the effect of pregravid weight and pregnancy weight gain on pregnancy outcomes in Cree women.

METHODS

We reviewed maternal and infant outcomes of the first pregnancy in Cree women living in James Bay, Quebec, from 1994 to 2000. We examined data from women who had a full-term singleton birth and a maternal pregravid body mass index (BMI) > or = 18.5 kg/m2 and whose weight had been recorded in the first trimester and within one month prior to delivery. Weight in the first trimester was used to estimate pregravid BMI.

RESULTS

Data were available for 603 women. At the beginning of pregnancy, 23.1% of the women had normal weight (BMI 18.5-24.9 kg/m2), 27.9% were overweight (BMI 25-29.9 kg/m2), and 49.1% were obese (BMI > or = 30 kg/m2). Nearly one-half of the women gained excessive weight in pregnancy. Adverse outcomes were less common in women with a normal pregravid BMI than in women with a pregravid BMI in the overweight or obese range. Obese women with excessive weight gain had a higher prevalence of preeclampsia (14.9%) than obese women with low (3.7%) or acceptable (6.3%) weight gain; however, obese women with excessive weight gain had a lower prevalence of gestational diabetes mellitus.

CONCLUSION

Interventions must be developed to prevent pregravid obesity and excessive weight gain in pregnancy in Cree women to improve maternal and fetal outcomes.

Secular trends in cesarean delivery rates among macrosomic deliveries in the United States, 1989 to 2002

OBJECTIVES

We describe national trends in cesarean delivery rates among macrosomic infants during 1989 to 2000 and evaluate the maternal characteristics and risk factors for macrosomic infants delivered by cesarean section as compared to macrosomic infants delivered vaginally.

STUDY DESIGN

We analyzed US 1989 to 2000 Natality files, selecting term (37 to 44 week) single live births to U.S. resident mothers. We compare macrosomic infants (4000 to 4499, 4500 to 4999 and 5000+ g infants) to a normosomic (3000 to 3999 g) control group.

RESULTS

The proportion of cesarean deliveries among 5000+ g infants increased significantly over the time period. The adjusted odds ratio of cesarean delivery increased for all macrosomic categories over the 12-year period, as compared to normal birth weight infants.

CONCLUSIONS

Rates of cesarean delivery among macrosomic infants continue to increase despite a lack of evidence of the benefits of cesarean delivery within this population. Further exploration of the rationale for this trend is warranted and should include the development of an optimal delivery strategy for such patients.

Sibling birthweight as a predictor of macrosomia in women with type 1 diabetes

AIMS/HYPOTHESIS

The aim of this study was to establish the value of maternal HbA1c levels and older sibling birthweight as predictors of birthweight and macrosomia in the offspring of women with type 1 diabetes.

SUBJECTS AND METHODS

A total of 214 pregnancies of 107 women with type 1 diabetes were studied. Regression analysis was performed to test the predictive value of the birthweight of the first-born infant, HbA(1)c levels, maternal BMI, maternal age and time between subsequent births on the birthweight of the second-born infant. Birthweights were corrected for sex and gestational age. The percentages of first- and second-born infants with macrosomia (weight >90th centile) were calculated and compared.

RESULTS

Only the birthweight of earlier born infants was significantly related to that of second-born infants (p<0.001) and 40-50% of the variation in the birthweight of second-born infants could be explained by the birthweight of the first-born infants. About 85% of the mothers who gave birth to a macrosomic infant had a macrosomic infant in a subsequent pregnancy.

CONCLUSIONS/INTERPRETATION

Although it is clear that glycaemic control contributes to birthweight in women with type 1 diabetes, the birthweight of an earlier born infant appears to be a much better predictor of the birthweight of a subsequent infant than HbA1c levels during pregnancy. It may, therefore, be used to identify patients at risk of giving birth to a macrosomic infant. Daily home monitoring of glucose levels, rather than HbA1c levels, should be used for assessment of maternal glycaemia during pregnancy.

Suspicion and treatment of the macrosomic fetus: a review

OBJECTIVE

To review the prevalence of and our ability to identify macrosomic (birthweight >4000 g) fetuses. Additionally, based on the current evidence, propose an algorithm for treatment of suspected macrosomia.

STUDY DESIGN

A review.

RESULTS

According to the National Vital Statistics, in the United States, the prevalence of newborns weighing at least 4000 g has decreased by 10% in seven years (10.2% in 1996 and 9.2% in 2002) and 19% for newborns with weights >5000 g (0.16% and 0.13%, respectively). Bayesian calculations indicates that the posttest probability of detecting a macrosomic fetus in an uncomplicated pregnancy is variable, ranging from 15% to 79% with sonographic estimates of birth weight, and 40 to 52% with clinical estimates. Among diabetic patients the post-test probability of identifying a newborn weighing >4000 g clinically and sonographically is over 60%. Among uncomplicated pregnancies, there is sufficient evidence that suspected macrosomia is not an indication for induction or for primary cesarean delivery. For pregnancies complicated by diabetes, with a prior cesarean delivery or shoulder dystocia, delivery of a macrosomic fetus increases the rate of complications, but there is insufficient evidence about the threshold of estimated fetal weight that should prompt cesarean delivery.

CONCLUSION

Due to the inaccuracies, among uncomplicated pregnancies suspicion of macrosomia is not an indication for induction or for primary cesarean delivery.

Big infants in the neonatal intensive care unit

OBJECTIVE

This study was undertaken to identify risk factors for prolonged neonatal intensive care unit (NICU) stay in macrosomic (> or = 4000 g) neonates.

STUDY DESIGN

A population-based case-control study in which 799 cases of macrosomic neonates with a prolonged NICU stay were compared with macrosomic neonates without a prolonged stay (n = 1598).

RESULTS

Significant risk factors included: 5-minute Apgar score less than 7: odds ratio (OR) = 43.1; fetal distress: OR = 3.0; birth length less than 20 inches: OR = 2.2; birth weight more than 5000 g: OR = 2.6; maternal diabetes: OR = 3.0; gestational age 37 to 38 weeks: OR = 2.2; cephalopelvic disproportion: OR = 2.5; primary cesarean: OR = 2.6; forceps/vacuum: OR = 1.7. No significant association was seen with labor induction/augmentation or dysfunctional/prolonged labor.

CONCLUSION

Prolonged stay in macrosomic neonates was related to fetal distress measures and less to factors related to prolonged labor. Attention to intrapartum fetal status during labor with suspected macrosomia appears to be especially warranted.

Risk factors and obstetric complications associated with macrosomia

OBJECTIVE

Macrosomia is associated with adverse maternal outcomes. The objective of this study was to characterize the epidemiology of macrosomia and related maternal complications.

METHOD

Live births (146,526) were identified between 1995 and 1999 in the Kaiser Permanente Medical Care Program's Northern California Region (KPMCP NCR) database. Bivariate and multivariate analyses were performed for risk factors and complications associated with macrosomia (birth weight >4500 g).

RESULT

Male infant sex, multiparity, maternal age 30-40, white race, diabetes, and gestational age >41 weeks were associated with macrosomia (p<0.001). In bivariate and multivariate analyses, macrosomia was associated with higher rates of cesarean birth, chorioamnionitis, shoulder dystocia, fourth-degree perineal lacerations, postpartum hemorrhage, and prolonged hospital stay (p<0.01).

CONCLUSION

Macrosomia was associated with adverse maternal outcomes in this cohort. More research is needed to determine how to prevent complications related to excessive birth weight.

Obstetric Outcome of Extreme Macrosomia

OBJECTIVE

To determine the effect of extreme macrosomia on perinatal outcome.

METHODS

We conducted a retrospective review of all deliveries with birth weight > or = 5000 g in a tertiary centre from 1986 to 2000 and analyzed the method of delivery and perinatal outcome.

RESULTS

Extreme macrosomia (birth weight > or = 5000 g) was coded in 111 deliveries. There were 62 deliveries by Caesarean section (CS) (25 in labour and 37 elective). The 49 vaginal deliveries were complicated by 10 (20%) cases of shoulder dystocia and 3 (6%) of Erb's palsy. Permanent Erb's palsy was noted in only 1 of these 3 cases. Shoulder dystocia was associated with use of oxytocin and instrumental deliveries.

CONCLUSION

Implementing the 2002 guidelines from the American College of Obstetricians and Gynecologists (that is, recommending Caesarean delivery of fetuses with an estimated weight of at least 5000 g) would have a negligible effect on the CS rate while eliminating 10 cases of shoulder dystocia in 49 births. A policy eliminating the use of oxytocin and instrumental deliveries would have prevented most birth traumas in this group. Unfortunately, this high-risk group is difficult to identify in the antepartum period, complicating the implementation of these guidelines and probably leading to higher rates of CS. In addition, the effect of endorsing such a policy on overall neonatal and maternal morbidity is minimal, because most morbidity occurs in newborns weighing less than 4000 g.

Gestational Weight Gain, Macrosomia, and Risk of Cesarean Birth in Nondiabetic Nulliparas

OBJECTIVE

To examine how the association between excessive weight gain and cesarean birth is modified by infant birth weight in nondiabetic women.

METHODS

We designed a retrospective cohort study of singleton, term, nulliparous women with cephalic presentations delivering at a single university hospital. Subjects with diabetes were excluded. Bivariate and multivariate analyses were performed. Regression models controlled for maternal age, maternal prepregnancy body mass index, gestational age, ethnicity, smoking, birth weight, and date of delivery.

RESULTS

Women gaining above Institute of Medicine guidelines were more likely to have a cesarean birth, even if birth weight was less than 4,000 g. In the multivariate analysis, women with excessive weight gain had an odds ratio of 1.40 (95% confidence interval 1.22-1.59) for cesarean birth. When absolute weight gain (total pregnancy weight gain minus birth weight and placental weight) was used in the multivariate analysis, excessive weight gain was still an independent predictor of cesarean delivery. Although macrosomia was a stronger predictor of cesarean than weight gain alone, excessive weight gain was much more common than macrosomia in our cohort.

CONCLUSION

Excessive weight gain during pregnancy is an independent risk factor for cesarean birth, even when birth weight is not excessive. Other mechanisms besides macrosomia may be involved in the association between high weight gain and cesarean birth. We estimate that of the approximately 288,000 primary cesarean deliveries performed in nulliparas annually in the United States, 64,000 would be prevented if no women gained above Institute of Medicine recommendations.

LEVEL OF EVIDENCE

II-2