Prenatal ultrasound biometry related to subsequent blood pressure in childhood

The associations of prenatal exposure to PM2.5 and its constituents with fetal growth: A prospective birth cohort in Beijing, China

BACKGROUND

Limited studies investigated the association of prenatal exposure to PM_2.5 and fetal growth measured by ultrasound with inconsistent results. No study evaluated the effect of PM_2.5 constituents on fetal growth in utero. We aimed to investigated whether prenatal exposure to PM_2.5 and its constituents was associated with fetal growth measured by ultrasound.

METHODS

A total of 4319 eligible pregnant women in Peking University Birth Cohort in Tongzhou (PKUBC-T) were included in the study. Based on mothers' residential addresses, we estimated prenatal PM_2.5 concentrations with a satellite-based spatiotemporal model and PM_2.5 constituents concentrations with a modified Community Multiscale Air Quality model. Fetal growth parameters of abdominal circumference (AC), head circumference (HC), and femur length (FL) were measured by ultrasound and then estimated fetal weight (EFW) was calculated. We calculated sex and gestational age-specific fetal growth Z-score and then defined the corresponding fetal undergrowth. Generalized estimating equation was used to investigate the association of PM_2.5 and its constituents with fetal growth Z-score and fetal undergrowth.

RESULTS

Prenatal exposure to PM_2.5, OC, EC, SO₄^2-, NH₄⁺, or NO₃^- was consistently associated with decreased Z-scores of fetal growth parameters (AC, HC, FL, EFW). One IQR increase of PM_2.5, OC, EC, SO₄^2-, NH₄⁺, or NO₃^- was associated with -0.183 [95% confident interval (CI): -0.225, -0.141], -0.144 (95%CI: -0.181, -0.107), -0.123 (95%CI: -0.160, -0.085), -0.035 (95%CI: -0.055, -0.015), -0.095 (95%CI: -0.126, -0.064), and -0.124 (95%CI: -0.159, -0.088) decrease in EFW Z-score, respectively. Prenatal exposure to PM_2.5, OC, EC, SO₄^2-, NH₄⁺, or NO₃^- was also associated with higher risk of fetal AC, HC, FL or EFW undergrowth.

CONCLUSION

The study identified that prenatal exposure to PM_2.5 or its constituents was associated with impaired fetal growth. The findings provided evidence that control measures for PM_2.5 constituents should be implemented for further promoting fetal growth.

Childhood vascular phenotypes have differing associations with prenatal and postnatal growth

OBJECTIVE

In children aged 8--9 years, we examined the associations of linear and abdominal circumference growth during critical stages of prenatal and postnatal development with six vascular measurements commonly used as early markers of atherosclerosis and later cardiovascular disease (CVD) risk.

METHODS

In 724 children from the UK Southampton Women's Survey mother--offspring cohort, offspring length/height and abdominal circumference measurements were collected at 10 ages between 11 weeks' gestation and age 8--9 years. Using residual growth modelling and linear regression, we examined the independent associations between growth and detailed vascular measures made at 8--9 years.

RESULTS

Postnatal linear and abdominal circumference growth were associated with higher childhood SBP and carotid--femoral pulse wave velocity, whereas prenatal growth was not. For example, 1SD faster abdominal circumference gain between ages 3 and 6 years was associated with 2.27 [95% confidence interval (CI): 1.56--2.98] mmHg higher SBP. In contrast, faster abdominal circumference gain before 19 weeks' gestation was associated with greater carotid intima--media thickness [0.009 mm (0.004--0.015) per 1SD larger 19-week abdominal circumference), whereas later growth was not. We found no strong associations between prenatal or postnatal growth and DBP or measures of endothelial function.

CONCLUSION

Higher postnatal linear growth and adiposity gain are related to higher SBP and carotid--femoral pulse wave velocity in childhood. In contrast, faster growth in early gestation is associated with greater childhood carotid intima--media thickness, perhaps resulting from subtle changes in vascular structure that reflect physiological adaptations rather than subclinical atherosclerosis.

The World Health Organization fetal growth charts: concept, findings, interpretation, and application

Ultrasound biometry is an important clinical tool for the identification, monitoring, and management of fetal growth restriction and development of macrosomia. This is even truer in populations in which perinatal morbidity and mortality rates are high, which is a reason that much effort is put onto making the technique available everywhere, including low-income societies. Until recently, however, commonly used reference ranges were based on single populations largely from industrialized countries. Thus, the World Health Organization prioritized the establishment of fetal growth charts for international use. New fetal growth charts for common fetal measurements and estimated fetal weight were based on a longitudinal study of 1387 low-risk pregnant women from 10 countries (Argentina, Brazil, Democratic Republic of Congo, Denmark, Egypt, France, Germany, India, Norway, and Thailand) that provided 8203 sets of ultrasound measurements. The participants were characterized by median age 28 years, 58% nulliparous, normal body mass index, with no socioeconomic or nutritional constraints (median caloric intake, 1840 calories/day), and had the ability to attend the ultrasound sessions, thus essentially representing urban populations. Median gestational age at birth was 39 weeks, and birthweight was 3300 g, both with significant differences among countries. Quantile regression was used to establish the fetal growth charts, which also made it possible to demonstrate a number of features of fetal growth that previously were not well appreciated or unknown: (1) There was an asymmetric distribution of estimated fetal weight in the population. During early second trimester, the distribution was wider among fetuses <50th percentile compared with those above. The pattern was reversed in the third trimester, with a notably wider variation >50th percentile. (2) Although fetal sex, maternal factors (height, weight, age, and parity), and country had significant influence on fetal weight (1-4.5% each), their effect was graded across the percentiles. For example, the positive effect of maternal height on fetal weight was strongest on the lowest percentiles and smallest on the highest percentiles for estimated fetal weight. (3) When adjustment was made for maternal covariates, there was still a significant effect of country as covariate that indicated that ethnic, cultural, and geographic variation play a role. (4) Variation between populations was not restricted to fetal size because there were also differences in growth trajectories. (5) The wide physiologic ranges, as illustrated by the 5th-95th percentile for estimated fetal weight being 2205-3538 g at 37 weeks gestation, signify that human fetal growth under optimized maternal conditions is not uniform. Rather, it has a remarkable variation that largely is unexplained by commonly known factors. We suggest this variation could be part of our common biologic strategy that makes human evolution extremely successful. The World Health Organization fetal growth charts are intended to be used internationally based on low-risk pregnancies from populations in Africa, Asia, Europe, and South America. We consider it prudent to test and monitor whether the growth charts' performance meets the local needs, because refinements are possible by a change in cut-offs or customization for fetal sex, maternal factors, and populations. In the same line, the study finding of variations emphasizes the need for carefully adjusted growth charts that reflect optimal local growth when public health issues are addressed.

Longitudinal growth during fetal life and infancy and cardiovascular outcomes at school-age

OBJECTIVE

Low birth weight is associated with cardiovascular disease. We examined the effects of fetal and infant growth patterns on cardiovascular outcomes in children.

METHODS

In a population-based prospective cohort study among 6239 children, we estimated fetal-femur length and weight by 20 and 30 weeks ultrasound, and child length and weight at birth, 0.5, 1, 2 and 6 years. We measured blood pressure (BP), carotid-femoral pulse wave velocity, aortic root diameter, left ventricular mass and fractional shortening at 6 years. We used regression analyses to identify longitudinal growth patterns associated with height-standardized vascular outcomes and body-surface-area-standardized cardiac outcomes.

RESULTS

Younger gestational age and lower birth weight were associated with higher BP, smaller aortic root diameter and lower left ventricular mass in childhood (all P values <0.05). Children with decelerated or normal fetal growth followed by accelerated infant growth had higher BP, whereas those with decelerated growth during both fetal life and infancy had a relatively larger left ventricular mass. Longitudinal growth analyses showed that children with increased BP tended to be smaller during third trimester of fetal life, but of normal size during infancy, than children with normal BP. Children with increased aortic root diameter or left ventricular mass tended to be larger during fetal life, but of similar size during infancy.

CONCLUSION

Specific fetal and infant growth patterns are associated with different cardiovascular outcomes in children. Further studies are needed to identify the underlying mechanisms and the long-term cardiovascular consequences.

Single and Serial Fetal Biometry to Detect Preterm and Term Small- and Large-for-Gestational-Age Neonates: A Longitudinal Cohort Study

Objectives

To assess the value of single and serial fetal biometry for the prediction of small- (SGA) and large-for-gestational-age (LGA) neonates delivered preterm or at term.

Methods

A cohort study of 3,971 women with singleton pregnancies was conducted from the first trimester until delivery with 3,440 pregnancies (17,334 scans) meeting the following inclusion criteria: 1) delivery of a live neonate after 33 gestational weeks and 2) two or more ultrasound examinations with fetal biometry parameters obtained at ≤36 weeks. Primary outcomes were SGA (<5^th centile) and LGA (>95^th centile) at birth based on INTERGROWTH-21^st gender-specific standards. Fetus-specific estimated fetal weight (EFW) trajectories were calculated by linear mixed-effects models using data up to a fixed gestational age (GA) cutoff (28, 32, or 36 weeks) for fetuses having two or more measurements before the GA cutoff and not already delivered. A screen test positive for single biometry was based on Z-scores of EFW at the last scan before each GA cut-off so that the false positive rate (FPR) was 10%. Similarly, a screen test positive for the longitudinal analysis was based on the projected (extrapolated) EFW at 40 weeks from all available measurements before each cutoff for each fetus.

Results

Fetal abdominal and head circumference measurements, as well as birth weights in the Detroit population, matched well to the INTERGROWTH-21^st standards, yet this was not the case for biparietal diameter (BPD) and femur length (FL) (up to 9% and 10% discrepancy for mean and confidence intervals, respectively), mainly due to differences in the measurement technique. Single biometry based on EFW at the last scan at ≤32 weeks (GA IQR: 27.4–30.9 weeks) had a sensitivity of 50% and 53% (FPR = 10%) to detect preterm and term SGA and LGA neonates, respectively (AUC of 82% both). For the detection of LGA using data up to 32- and 36-week cutoffs, single biometry analysis had higher sensitivity than longitudinal analysis (52% vs 46% and 62% vs 52%, respectively; both p<0.05). Restricting the analysis to subjects with the last observation taken within two weeks from the cutoff, the sensitivity for detection of LGA, but not SGA, increased to 65% and 72% for single biometry at the 32- and 36-week cutoffs, respectively. SGA screening performance was higher for preterm (<37 weeks) than for term cases (73% vs 46% sensitivity; p<0.05) for single biometry at ≤32 weeks.

Conclusions

When growth abnormalities are defined based on birth weight, growth velocity (captured in the longitudinal analysis) does not provide additional information when compared to the last measurement for predicting SGA and LGA neonates, with both approaches detecting one-half of the neonates (FPR = 10%) from data collected at ≤32 weeks. Unlike for SGA, LGA detection can be improved if ultrasound scans are scheduled as close as possible to the gestational-age cutoff when a decision regarding the clinical management of the patient needs to be made. Screening performance for SGA is higher for neonates that will be delivered preterm.

Nutrition for Multiples

In 2012 there were 135,943 infants of multiple pregnancies born in the United States, nearly a 2-fold increase since 1980, with twins accounting for 96% of all multiple births. To date, most perinatal morbidities associated with multiple births have proven resistant to technological or pharmaceutical interventions. Maternal nutrition can have a profound effect on the course and outcome of multiple pregnancy, with the goal of achieving optimal intrauterine growth and birthweights, and minimizing prenatal and perinatal complications for the mother and her children.

National curves of foetal growth in singleton foetuses of Greek origin

BACKGROUND

Foetal growth monitoring is an essential component of prenatal care with postnatal impact. The aim of the study was to construct reference ranges for foetal biometric parameters in Greek foetuses and to compare them with previously published models.

MATERIALS AND METHODS

Measurements from 1200 Greek foetuses were used to construct normal curves for biparietal diameter (BPD), occipitofrontal diameter (OFD), head circumference (HC), abdominal circumference (AC), femoral length (FL) and the BPD/FL ratio according to the methodology described by Royston and Wright (1998). The model was validated in a second group of 1200 different foetuses using analysis of the corresponding standardized residuals (z-scores). The z-scores which were derived by our model were compared to those calculated using previously published models from other populations.

RESULTS

BPD, OFD, HC, AC, FL and the BPD/FL ratio are accurately described by simple quadratic equations (R(2) > 0·96 for most of the parameters tested). Statistically significant differences were observed for most of the z-scores when our models were compared to previously published models. Less than 10% of our foetuses were < 5th or > 95th centile of the latter models. About 10% of our foetuses were > 95th centile for FL and HC when the INTERGROWTH-21st formulas were used.

CONCLUSION

We present national foetal biometric references. Using charts from other populations (including INTERGROWTH-21st) may be unrepresentative of local populations and lead to misclassification of foetal growth status.

Vitamin D deficiency at 16 to 20 weeks' gestation is associated with impaired lung function and asthma at 6 years of age

RATIONALE

Vitamin D deficiency is associated with chronic lung disease. We have previously shown in an in vivo mouse model that maternal vitamin D deficiency is associated with alterations in early life lung structure and function. However, there are limited data to support a relationship between maternal vitamin D deficiency during the early stages of lung development and postnatal lung function in human populations.

OBJECTIVES

To assess the association between maternal vitamin D deficiency, postnatal lung function, and asthmatic status in a longitudinal birth cohort.

METHODS

Serum was collected at 16 to 20 weeks' gestation at the time of recruitment in a community-based prospective birth cohort for measurement of vitamin D (25[OH]D). Lung function was assessed by spirometry according to American Thoracic Society guidelines in children at 6 and 14 years of age. Demographic and clinical history data were collected by questionnaire at recruitment and at the follow-up visits.

MEASUREMENTS AND MAIN RESULTS

FVC Z-scores in both sexes (β, 0.007 [95% confidence interval (CI), 0.001-0.013]; P = 0.02) and FEV1 Z-scores in girls (β, 0.007 [95% CI, 0.001-0.013]; P = 0.02) were positively associated with maternal serum 25(OH)D at 6 years of age. These associations were mostly absent at 14 years of age. Maternal vitamin D deficiency was positively associated with asthma at 6 years of age but only in boys (odds ratio, 3.03 [95% CI, 1.02-9.02]; P = 0.04).

CONCLUSIONS

This study supports the notion that vitamin D deficiency during lung development may impact on postnatal lung growth and increase the risk of developing lung disease.

Fetal ultrasound measurements and associations with postnatal outcomes in infancy and childhood: a systematic review of an emerging literature

BACKGROUND

Several hypotheses predict that faltering fetal growth is an antecedent for common non-communicable diseases. This is the first systematic review of an emerging literature linking antenatal fetal measurements to postnatal outcomes.

METHODS

Electronic databases (OVID, EMBASE and Google Scholar) and cohort study websites were searched in July 2014. Studies were selected which examined associations between antenatal fetal ultrasound measurements and postnatal outcomes. Neonatal outcomes, e.g. premature delivery, were not included.

RESULTS

There were 23 papers identified from cohorts in Western countries, including 11 from a single cohort. Four papers reported outcomes in children aged over 6 years. Small, but not large, for gestational age (SGA) was associated with adverse outcomes except for one study where individuals with the lightest or heaviest estimated fetal weight risk were at increased risk for autistic spectrum disorder. The magnitude of associations was modest, e.g. each z score reduction in fetal size was associated with 10-20% increased risk for delayed development or a 1 mm Hg increase in blood pressure. Both growth acceleration and deceleration were both associated with adverse outcomes.

CONCLUSIONS

There is consistency for antenatal SGA and growth deceleration being associated with adverse outcomes determined in early childhood. Accelerating fetal growth was associated with both advantageous and disadvantageous outcomes, and this is consistent with the concept of predictive adaptive responses where exposure to a postnatal environment which was not anticipated predisposes the fetus to adverse health.

WHO multicentre study for the development of growth standards from fetal life to childhood: the fetal component

Background

In 2006 WHO presented the infant and child growth charts suggested for universal application. However, major determinants for perinatal outcomes and postnatal growth are laid down during antenatal development. Accordingly, monitoring fetal growth in utero by ultrasonography is important both for clinical and scientific reasons. The currently used fetal growth references are derived mainly from North American and European population and may be inappropriate for international use, given possible variances in the growth rates of fetuses from different ethnic population groups. WHO has, therefore, made it a high priority to establish charts of optimal fetal growth that can be recommended worldwide.

Methods

This is a multi-national study for the development of fetal growth standards for international application by assessing fetal growth in populations of different ethnic and geographic backgrounds. The study will select pregnant women of high-middle socioeconomic status with no obvious environmental constraints on growth (adequate nutritional status, non-smoking), and normal pregnancy history with no complications likely to affect fetal growth. The study will be conducted in centres from ten developing and industrialized countries: Argentina, Brazil, Democratic Republic of Congo, Denmark, Egypt, France, Germany, India, Norway, and Thailand. At each centre, 140 pregnant women will be recruited between 8 + 0 and 12 + 6 weeks of gestation. Subsequently, visits for fetal biometry will be scheduled at 14, 18, 24, 28, 32, 36, and 40 weeks (+/− 1 week) to be performed by trained ultrasonographers.

The main outcome of the proposed study will be the development of fetal growth standards (either global or population specific) for international applications.

Discussion

The data from this study will be incorporated into obstetric practice and national health policies at country level in coordination with the activities presently conducted by WHO to implement the use of the Child Growth Standards.

Investigating the relationship between prenatal growth and postnatal outcomes: a systematic review of the literature

Theories regarding the relationship between pre- and postnatal growth and programming of health have been based on characteristics at birth, with little or no reference to the patterns of growth occurring in utero. Review of the literature to identify studies using ultrasonographically obtained fetal dimensions to track prenatal growth and relate these patterns of growth to postnatal anthropometry and cardiovascular and metabolic risk factors. Review of Medline, Scopus and Proquest for studies reporting on ultrasonographically derived estimates of fetal growth and their association with postnatal anthropometry, body composition or cardiovascular and metabolic risk factors. Quality of papers were assessed using the method developed by Downs and Black. Twenty-nine studies met the inclusion criteria, with a mean score of high quality. Twenty of the studies had follow-up in infancy, five in childhood, three in adolescence and one in adulthood. The associations observed suggest that centile tracking may occur early in pregnancy though whether this is as early as the first trimester is uncertain. The second trimester may be a critical period for the programming of blood pressure and abdominal circumference may be the most sensitive fetal dimension to indicate any programming.

Second trimester estimated fetal weight and fetal weight gain predict childhood obesity

OBJECTIVE

To determine the extent to which fetal weight during mid-pregnancy and fetal weight gain from mid-pregnancy to birth predict adiposity and blood pressure (BP) at age 3 years.

STUDY DESIGN

Among 438 children in the Project Viva cohort, we estimated fetal weight at 16-20 (median 18) weeks' gestation using ultrasound biometry measures. We analyzed fetal weight gain as change in quartile of weight from the second trimester until birth, and we measured height, weight, subscapular and triceps skinfold thicknesses, and BP at age 3.

RESULTS

Mean (SD) estimated weight at 16-20 weeks was 234 (30) g and birth weight was 3518 (420) g. In adjusted models, weight estimated during the second trimester and at birth were associated with higher body mass index (BMI) z-scores at age 3 years (0.32 unit [95% CI, 0.04-0.60 unit] and 0.53 unit [95% CI, 0.24-0.81 unit] for the highest vs lowest quartile of weight). Infants with more rapid fetal weight gain and those who remained large from mid-pregnancy to birth had higher BMI z-scores (0.85 unit [95% CI, 0.30-1.39 unit] and 0.63 unit [95% CI, 0.17-1.09 unit], respectively) at age 3 than did infants who remained small during fetal life. We did not find associations between our main predictors and sum or ratio of subscapular and triceps skinfold thicknesses or systolic BP.

CONCLUSION

More rapid fetal weight gain and persistently high fetal weight during the second half of gestation predicted higher BMI z-score at age 3 years. The rate of fetal weight gain throughout pregnancy may be important for future risk of adiposity in childhood.

Maternal and paternal height and BMI and patterns of fetal growth: the Pune Maternal Nutrition Study

We examined the differential associations of each parent's height and BMI with fetal growth, and examined the pattern of the associations through gestation. Data are from 557 term pregnancies in the Pune Maternal Nutrition Study. Size and conditional growth outcomes from 17 to 29 weeks to birth were derived from ultrasound and birth measures of head circumference, abdominal circumference, femur length and placental volume (at 17 weeks only). Parental height was positively associated with fetal head circumference and femur length. The associations with paternal height were detectible earlier in gestation (17-29 weeks) compared to the associations with maternal height. Fetuses of mothers with a higher BMI had a smaller mean head circumference at 17 weeks, but caught up to have larger head circumference at birth. Maternal but not paternal BMI, and paternal but not maternal height, were positively associated with placental volume. The opposing associations of placenta and fetal head growth with maternal BMI at 17 weeks could indicate prioritisation of early placental development, possibly as a strategy to facilitate growth in late gestation. This study has highlighted how the pattern of parental-fetal associations varies over gestation. Further follow-up will determine whether and how these variations in fetal/placental development relate to health in later life.

The effect of birthweight upon insulin resistance and associated cardiovascular risk factors in adolescence is not explained by fetal growth velocity in the third trimester as measured by repeated ultrasound fetometry

AIMS/HYPOTHESIS

Smallness for gestational age (SGA) is associated with increased risk of developing components of the metabolic syndrome. Although SGA can imply intrauterine growth restriction (IUGR), more information is required to link specific fetal growth patterns to adult outcomes.

METHODS

We examined the impact of fetal growth velocity during the third trimester (FGV) vs birthweight for gestational age on early markers of the metabolic syndrome in 123 healthy men and women (mean age 17.5 years) born at term. FGV was determined by ultrasound measurements.

RESULTS

After correction for confounders including current BMI, SGA was significantly associated with raised basal plasma insulin (+19% above appropriate for gestational age), homeostasis model assessment of insulin resistance (+21%), cholesterol:HDL-cholesterol ratio (+13%) and systolic BP (+4.8%) (all p < 0.05). Furthermore SGA was associated with increased fat mass (+9.6%) and trunk-fat per cent (+6.8%) and with reduced lean body mass as determined by dual-energy X-ray absorptiometry scans (-4.1% below appropriate for gestational age) (all p < 0.05). In contrast, IUGR in the third trimester was associated only with an elevated cholesterol:HDL-cholesterol ratio (+11% above not-IUGR).

CONCLUSIONS/INTERPRETATION

In the present study, FGV did not explain the impact of birthweight upon the metabolic phenotype in adolescence. This suggests that fetal growth prior to the third trimester or postnatal catch-up growth plays a more important role.

Improving outcomes in pregnancy

What are the implications of first trimester fetal growth and racial origin?

Anterior-posterior thigh diameter measured by two-dimensional sonography: indicator of fetal age at 18 to 28 weeks gestation ?

OBJECTIVE

Little published research exists in the area of fetal thigh biometry, specifically in the use of the anteriorposterior fetal thigh diameter (APTD). A continuing review of existing practices needs to be coupled with evaluation of alternate or additional methodology. This study evaluated the usefulness and direct correlation of a simple, new method of predicting fetal age by measurement of the anterior-posterior thigh diameter (APTD) in a normal 18-to 28 week pregnancies using two-dimensional sonography.

METHODS

This was a quantitative prospective study of 55 patients in the High Level General Hospital, Alberta, Canada. Anterior-posterior thigh diameters (APTD) were sonographically measured and the normal range for each week of pregnancy was determined five times for reliability.

RESULTS

Significant correlation was found between (APTD) and fetal age from simple line regression analysis, with >99.9% confidence intervals at each week from 18 to 28 weeks gestation. There was a correlation of 1 mm APTD per 1 week of fetal age. The standard error of estimation was very low at (0.08664) in edition (r>0.9993) and (p < than 0.0001). The residual scatter plots confirmed the APTD validity.

CONCLUSION

APTD is a reliable and valid method for assessing fetal age in a normal pregnancy and may be particularly useful when other parameters are unable accurately to predict fetal age. An accurate linear measurement of multiple fetal parameters allows a more complete profile of fetal growth and estimated date of delivery (EDD). APTD may also be useful in identifying fetal growth problems. All of the values of fetal age lie directly on the "best-fit" regression line. Since the coefficient of determination (Rsq) is very high, this model is very effective.

The twin placenta: framework for gross analysis in fetal origins of adult disease initiatives

Current data strongly support that a wide variety of adult health risks are influenced by intrauterine life events. Twins may have the same (identical, monozygous) or different (fraternal, dizygous) genes, but their relationship to their outside world, via their placentas, is rarely equal. Monochorionic twins and dichorionic twins both resemble and differ from singletons. In the balance between the similarities and the differences, we may find the answer to the interpretation of twin studies, and appropriately apply them to the 'fetal origins' hypothesis.

Fetal phenotypes and neonatal and early childhood outcomes in twins

OBJECTIVES

The purpose of this study was to evaluate factors associated with, and postnatal consequences of, altered patterns of fetal growth in twins.

STUDY DESIGN

Fetal growth was measured at 28 weeks' gestation on 218 twins, including head circumference, abdominal circumference, and femur length, and characterized as > or < or =10th %ile; children were followed up until the age of three years. Logistic regression was used to generate odds ratios of perinatal factors associated with reduced fetal growth.

RESULTS

Maternal height <62 inches was associated with reductions in femur length (adjusted odds ratio [AOR] 3.88, 95% CI 1.42-10.57) and abdominal circumference (AOR 8.63, 95% CI 2.41-30.94), while primiparity had a protective effect on both of these fetal measurements (AOR 0.28, 95% CI 0.13-0.64, and AOR 0.18, 95% CI 0.06-0.60, respectively), as well as head circumference (AOR 0.32, 95% CI 0.15-0.69). Smoking adversely affected femur and head growth (AOR 24.10, 95% CI 3.69-157.57, and AOR 10.82, 95% CI 1.73-67.79, respectively). Fetal reduction adversely affected femur and abdomen growth (AOR 5.85, 95% CI 1.52-22.51 and AOR 4.90, 95% CI 1.01-23.86, respectively), and monochorionicity and maternal weight gain <0.65 lb/wk before 20 weeks adversely affected femur growth (AOR 5.47, 95% CI 1.65-18.10, and AOR 3.39, 95% CI 1.34-8.59, respectively). At age 3 years, all categories of twins with reduced growth by 28 weeks' gestation were significantly shorter in height, and those with reduced abdominal circumference or head circumference at 28 weeks were also significantly lighter in weight compared with twins with adequate fetal growth by 28 weeks' gestation.

CONCLUSION

These data identify short maternal height, smoking, monochorionicity, fetal reduction, and inadequate weight gain before 20 weeks as risk factors associated with reduced twin fetal growth by 28 weeks' gestation and significant residual reductions in height and weight through 3 years of age.

Randomized controlled trial of prenatal zinc supplementation and fetal bone growth

BACKGROUND

Maternal zinc deficiency is relatively common in developing countries, but its consequences for fetal growth are not established.

OBJECTIVE

The goal was to examine whether improvement in maternal gestational zinc status is positively associated with fetal growth as assessed by ultrasonography.

DESIGN

We conducted a double-masked, randomized trial among 242 pregnant Peruvian women in an impoverished shantytown in Lima, Peru. At 10-16 wk of gestation, the women were randomly assigned to receive daily supplements containing 60 mg Fe and 250 microg folic acid, with or without 25 mg Zn. We measured fetal head circumference, biparietal diameter, abdominal circumference, and femur diaphysis length at 20, 24, 28, 32, 36, and 38 wk of gestation. Fetal measures were analyzed longitudinally to evaluate differences in trends of fetal growth by supplement type, and within-subject correlations were taken into account.

RESULTS

Femur diaphysis length was greater in fetuses whose mothers received zinc supplements (P < 0.05), and the difference tended to increase with gestational age. No significant differences by supplement type were observed for the other anatomical sites measured.

CONCLUSIONS

The observed positive effect of prenatal zinc on fetal femur diaphysis length is consistent with the results of experimental studies in animals and in vitro. The supplementation effect represents an upward shift in mean femur diaphysis length at term of about one-quarter of the reference SD. These findings suggest the potential importance of maternal zinc status for fetal bone growth in humans and illustrate the value of ultrasonography for evaluating the effect of prenatal nutritional interventions on components of fetal growth.

Timing is everything: a reconsideration of fetal growth velocity patterns identifies the importance of individual and sex differences

Fetal growth has been posited to follow a "timing hypothesis" sequence in which the second trimester favors a single growth velocity peak in body length and the third trimester accommodates a single growth velocity peak in weight accrual. To our knowledge, this proposition has never been tested with high-frequency longitudinal ultrasound data from normally growing human fetuses. The present study examined whether fetal growth in leg length had its peak velocity at or about 20-26 gestational weeks and declined subsequently and whether estimated fetal weight velocity was maximal at or about 33 weeks and declined subsequently; if the greatest acquisition of leg length occurred in the second trimester and weight in the third trimester; and if birth outcomes reflected these relationships. The data in this study included approximately weekly longitudinal ultrasound data collected from 44 maternal/fetal pairs in Brussels, Belgium. Diaphyseal lengths of the femur and tibia provided information on leg growth and estimated fetal weight was assessed from the biparietal and occipital-frontal head diameters and transverse and anterior-posterior diameters of the abdomen. Growth patterns were investigated from individual growth curves derived from daily growth velocity z-scores. Paired t-tests compared individuals' trimestral increments in leg length and fetal weight. Least-squares regression models employing the robust procedure for repeated measurements were used to test for relationships between trimester, size, growth rates, and birth outcome, controlling for day of measurement, sex, maternal smoking, and gestational age at birth. The normal fetuses in this study grew by pulsatile patterns of leg and estimated weight acquisition, not a single peak and decline process. Greater incremental growth in estimated fetal weight occurred during the second trimester and leg length in the third trimester. Individual and sex effects were significant in growth velocity patterns. Girls grew with greater synchrony between leg and weight growth and were accelerated by comparison with boys, with faster leg growth predicting lower ponderal index by the second trimester. Birth outcomes were sex-specific in timing effects and predictive variables. These results support the importance of sex-specific analyses, reemphasize the common notion that girls grow faster than boys, and direct attention to cross-talk between energy resources and growth.

Nutritional interventions during pregnancy for the prevention or treatment of impaired fetal growth: an overview of randomized controlled trials

This paper reviews the efficacy of nutrition interventions to prevent or treat impaired fetal growth. Searches were made for Cochrane systematic reviews and randomized controlled trials published before October 2002. Balanced protein energy supplementation reduced the risk of small for gestational age (SGA) by 30% (95%CI: 20% to 43%) while one trial conducted in New York, U.S., reported a negative effect of high protein supplementation on SGA (RR 1.58; 95%CI: 1.03-2.41). Calcium supplementation protected against low birth weight (RR 0.83; 95%CI: 0.71-0.98). Micronutrient supplements did not affect birth weight, except for magnesium supplementation, which reduced the risk of SGA by 30%. This finding, however, needs or be interpreted with caution because of methodological issues in the data analysis. Programmatic recommendations can be made only for intervening with balanced protein energy supplements, especially in population with a high prevalence of undernutrition. Research is needed to determine the efficacy of multiple micronutrient supplementation and the effect of single micronutrients supplementation on specific growth outcomes such as fetal organ and bone growth. In addition, the public health relevance of these outcomes and their relation to morbidity need to be evaluated.