Darios Getahun, Cande V Ananth, Wendy L Kinzler
Risk factors for antepartum and intrapartum stillbirth: a population-based study.
Am J Obstet Gynecol. 2007 Jun;196(6):499-507. doi: 10.1016/j.ajog.2006.09.017.
Abstract/Text
To examine disparities in risk factors for stillbirths and its occurrence in the antepartum versus intrapartum periods. A population-based, cross-sectional study using data on women that delivered singleton births between 20 and 43 weeks in Missouri (1989-1997) was conducted (n = 626,883). Hazard ratios and 95% confidence intervals were derived from regression models and population attributable fractions were estimated to examine the impact of risk factors on stillbirth. Among African Americans, risks of antepartum and intrapartum stillbirth were 5.6 and 1.1 per 1,000 singleton births, respectively; risks among whites were 3.4 and 0.5 per 1,000 births, respectively. Maternal age > or = 35 years, lack of prenatal care, prepregnancy body mass index (BMI) > or = 30 kg/m2, and prior preterm or small-for-gestational age birth were significantly associated with increased risk for antepartum stillbirth among whites, but not African Americans. BMI < or = 18.5 kg/m2 was associated with antepartum and intrapartum stillbirth among African Americans, but not whites. The presence of any congenital anomaly, abruption, and cord complications were associated with antepartum stillbirth in both races. Premature rupture of membranes was associated with intrapartum stillbirth among whites and African Americans, but intrapartum fever was associated with intrapartum stillbirth among African Americans. These risk factors were implicated in 54.9% and 19.7% of antepartum and intrapartum stillbirths, respectively, among African American women, and in a respective 46.6% and 11.9% among white women. Considerable heterogeneity in risk factors between antepartum and intrapartum stillbirths is evident. Knowledge on timing of stillbirth specific risk factors may help clinicians in decreasing antepartum and intrapartum stillbirth risks through monitoring and timely intervention.
Anne Ego, Damien Subtil, Gilles Grange, Olivier Thiebaugeorges, Marie-Victoire Senat, Christophe Vayssiere, Jennifer Zeitlin
Customized versus population-based birth weight standards for identifying growth restricted infants: a French multicenter study.
Am J Obstet Gynecol. 2006 Apr;194(4):1042-9. doi: 10.1016/j.ajog.2005.10.816.
Abstract/Text
OBJECTIVE: This study was undertaken to describe the characteristics of pregnancies according to a customized definition of fetal growth restriction and to determine the association between customized standards and adverse pregnancy outcomes.
STUDY DESIGN: Two definitions of growth restriction, a population and a customized standard, were applied to 56,606 births in 5 tertiary maternity hospitals in France from 1997 to 2002. The customized definition was adjusted for maternal height and weight, parity, fetal gender, and gestational age. Odds ratios and 95% CIs for neonatal morbidity and mortality were calculated to compare small for gestational age and non-small for gestational age births.
RESULTS: By using customized standards, 2.7% of births were reclassified as small for gestational age. These births were to taller, heavier, multiparous women. Compared with non-small for gestational age births, these newly detected small-for-gestational-age newborn infants showed an increased risk of stillbirth (odds ratio = 4.52, 95% CI 2.47-8.14) and perinatal death (odds ratio = 2.60, 95% CI 1.62-4.15). These infants were also more likely to be born to women with hypertensive disease in pregnancy (7.0%) versus those reclassified as non-small for gestational age (2.3%) and those non-small for gestational age by both standards (5.5%).
CONCLUSION: These findings highlight the interest of using customized birth weight standard adjusted for maternal and neonatal characteristics to identify fetuses at risk, particularly among apparently normal fetuses. Individual growth norms should be used to define small for gestational age.
Fetal Growth Restriction: ACOG Practice Bulletin, Number 227.
Obstet Gynecol. 2021 Feb 1;137(2):e16-e28. doi: 10.1097/AOG.0000000000004251.
Abstract/Text
Fetal growth restriction, also known as intrauterine growth restriction, is a common complication of pregnancy that has been associated with a variety of adverse perinatal outcomes. There is a lack of consensus regarding terminology, etiology, and diagnostic criteria for fetal growth restriction, with uncertainty surrounding the optimal management and timing of delivery for the growth-restricted fetus. An additional challenge is the difficulty in differentiating between the fetus that is constitutionally small and fulfilling its growth potential and the small fetus that is not fulfilling its growth potential because of an underlying pathologic condition. The purpose of this document is to review the topic of fetal growth restriction with a focus on terminology, etiology, diagnostic and surveillance tools, and guidance for management and timing of delivery.
Copyright © 2020 by the American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.
C C Lees, T Stampalija, A Baschat, F da Silva Costa, E Ferrazzi, F Figueras, K Hecher, J Kingdom, L C Poon, L J Salomon, J Unterscheider
ISUOG Practice Guidelines: diagnosis and management of small-for-gestational-age fetus and fetal growth restriction.
Ultrasound Obstet Gynecol. 2020 Aug;56(2):298-312. doi: 10.1002/uog.22134.
Abstract/Text
J M Pearce, S Campbell
A comparison of symphysis-fundal height and ultrasound as screening tests for light-for-gestational age infants.
Br J Obstet Gynaecol. 1987 Feb;94(2):100-4. doi: 10.1111/j.1471-0528.1987.tb02333.x.
Abstract/Text
The clinical efficiency of serial measurement of symphysis-fundal height (SFH) for the prediction of light-for-gestational age (LGA) infants was compared with that of a single measurement of fetal abdominal circumference (AC) by ultrasound in the third trimester. To make the tests comparable the lower cut-off point of AC was altered until the specificity matched that of SFH. The sensitivity of the AC measurement (83%) was slightly better than that of the SFH measurement (76%) but this difference was not statistically significant. Each test had a false positive rate of about 60% which is comparable with clinical assessment. Screening with both tests and predicting LGA with abnormal results from either test improved the sensitivity to 93% but, as expected, decreased the specificity to 67% and the positive predictive value to 32%. If ultrasound facilities permit both tests should be used otherwise SFH measurements only could screen for LGA with ultrasound back-up for those with low SFH results.
Andrew C G Breeze, Christoph C Lees
Prediction and perinatal outcomes of fetal growth restriction.
Semin Fetal Neonatal Med. 2007 Oct;12(5):383-97. doi: 10.1016/j.siny.2007.07.002. Epub 2007 Aug 31.
Abstract/Text
Assessment of fetal growth and wellbeing is one of the major purposes of antenatal care. Some fetuses have smaller than expected growth in utero and while some of these fetuses are constitutionally small, others have failed to meet their growth potential, that is they are growth restricted. While severe growth restriction is uncommon, the consequences of it being undetected may include perinatal death or severe morbidity. It is, therefore, important to have strategies in place to detect the fetus at risk of growth restriction. These would include an assessment of 'prior risk' from maternal history and examination combined with the results of biochemical and ultrasound investigations, the most promising of which are uterine artery Doppler and biochemistry. We discuss some of the factors to consider when stratifying the obstetric population into degrees of likelihood for growth restriction, and discuss aspects of the management and outcome of pregnancies complicated by growth restriction.
D D McIntire, S L Bloom, B M Casey, K J Leveno
Birth weight in relation to morbidity and mortality among newborn infants.
N Engl J Med. 1999 Apr 22;340(16):1234-8. doi: 10.1056/NEJM199904223401603.
Abstract/Text
BACKGROUND: At any given gestational age, infants with low birth weight have relatively high morbidity and mortality. It is not known, however, whether there is a threshold weight below which morbidity and mortality are significantly greater, or whether that threshold varies with gestational age.
METHODS: We analyzed the neonatal outcomes of death, five-minute Apgar score, umbilical-artery blood pH, and morbidity due to prematurity for all singleton infants delivered at Parkland Hospital, Dallas, between January 1, 1988, and August 31, 1996. A distribution of birth weights according to week of gestation at birth was created. Infants in the 26th through 75th percentiles for weight served as the reference group. Data on preterm infants (those born at 24 to 36 weeks of gestation) were analyzed separately from data on infants delivered at term (37 or more weeks of gestation).
RESULTS: A total of 122,754 women and adolescents delivered singleton live infants without malformations between 24 and 43 weeks of gestation. Among the 12,317 preterm infants who were analyzed, there was no specific birth-weight percentile at which morbidity and mortality increased. Among 82,361 infants who were born at term and whose birth weights were at or below the 75th percentile, however, the rate of neonatal death increased from 0.03 percent in the reference group (26th through 75th percentile for weight) to 0.3 percent for those with birth weights at or below the 3rd percentile (P<0.001). The incidence of five-minute Apgar scores of 3 or less and umbilical-artery blood pH values of 7.0 or less was approximately doubled for infants at or below the 3rd birth-weight percentile (P=0.003 and P<0.001, respectively). The incidence of intubation at birth, seizures during the first day of life, and sepsis was also significantly increased among term infants with birth weights at or below the 3rd percentile. These differences persisted after adjustment for the mother's race and parity and the infant's sex.
CONCLUSIONS: Mortality and morbidity are increased among infants born at term whose birth weights are at or below the 3rd percentile for their gestational age.
GRIT Study Group
A randomised trial of timed delivery for the compromised preterm fetus: short term outcomes and Bayesian interpretation.
BJOG. 2003 Jan;110(1):27-32.
Abstract/Text
OBJECTIVES: To compare the effect of delivering early to pre-empt terminal hypoxaemia with delaying for as long as possible to increase maturity.
DESIGN: A randomized controlled trial.
SETTING: 69 hospitals in 13 European countries.
PARTICIPANTS: Pregnant women with fetal compromise between 24 and 36 weeks, an umbilical artery Doppler waveform recorded and clinical uncertainty whether immediate delivery was indicated.
METHODS: The interventions were 'immediate delivery' or 'delay until the obstetrician is no longer uncertain'. The data monitoring and analysis were Bayesian.
MAIN OUTCOME MEASURES: 'Survival to hospital discharge' and 'developmental quotient at two years of age', this latter to be reported later.
RESULTS: Of 548 women (588 babies) recruited, outcomes were available on 547 mothers (587 babies). The median time-to-delivery intervals were 0.9 days in the immediate group and 4.9 days in the delay group. Total deaths prior to discharge were 29 (10%) in the immediate group versus 27 (9%) in the delay group (odds ratio 1.1, 95% CI 0.61-1.8). Total caesarean sections were 249 (91%) in the immediate group versus 217 (79%) in the delay group: (OR 2.7; 95% CI 1.6-4.5). These odds ratios were similar for those randomized at gestational ages above or below 30 weeks.
INTERPRETATION: The lack of difference in overall mortality suggests that clinicians participating in this trial were on average prepared to randomize at about the correct equivocal threshold between delivery and delay. However, there was insufficient evidence to convince enthusiasts for either immediate or delayed delivery that they were wrong.
J G Thornton, J Hornbuckle, A Vail, D J Spiegelhalter, M Levene, GRIT study group
Infant wellbeing at 2 years of age in the Growth Restriction Intervention Trial (GRIT): multicentred randomised controlled trial.
Lancet. 2004 Aug 7-13;364(9433):513-20. doi: 10.1016/S0140-6736(04)16809-8.
Abstract/Text
BACKGROUND: Although delivery is widely used for preterm babies failing to thrive in utero, the effect of altering delivery timing has never been assessed in a randomised controlled trial. We aimed to compare the effect of delivering early with delaying birth for as long as possible.
METHODS: 548 pregnant women were recruited by 69 hospitals in 13 European countries. Participants had fetal compromise between 24 and 36 weeks, an umbilical-artery doppler waveform recorded, and clinical uncertainty about whether immediate delivery was indicated. Before birth, 588 babies were randomly assigned to immediate delivery (n=296) or delayed delivery until the obstetrician was no longer uncertain (n=292). The main outcome was death or disability at or beyond 2 years of age. Disability was defined as a Griffiths developmental quotient of 70 or less or the presence of motor or perceptual severe disability. Analysis was by intention-to-treat. This trial has been assigned the International Standard Randomised Controlled Trial Number ISRCTN41358726.
FINDINGS: Primary outcomes were available on 290 (98%) immediate and 283 (97%) deferred deliveries. Overall rate of death or severe disability at 2 years was 55 (19%) of 290 immediate births, and 44 (16%) of 283 delayed births. With adjustment for gestational age and umbilical-artery doppler category, the odds ratio (95% CrI) was 1.1 (0.7-1.8). Most of the observed difference was in disability in babies younger than 31 weeks of gestation at randomisation: 14 (13%) immediate versus five (5%) delayed deliveries. No important differences in the median Griffiths developmental quotient in survivors was seen.
INTERPRETATION: The lack of difference in mortality suggests that obstetricians are delivering sick preterm babies at about the correct moment to minimise mortality. However, they could be delivering too early to minimise brain damage. These results do not lend support to the idea that obstetricians can deliver before terminal hypoxaemia to improve brain development.
