Are selection criteria for healthy pregnancies responsible for the gap between fetal growth in the French national Elfe birth cohort and the Intergrowth-21st fetal growth standards?

Which fetal growth charts should be used in France? Position of the French College of Obstetricians and Gynecologists (CNGOF)

OBJECTIVE

To assess which fetal growth charts best describe intrauterine growth in France defined as the ability to classify 10% of fetuses below the 10th percentile (small for gestational age [SGA]) and above the 90th percentile (large for gestational age [LGA]) in the second and third trimesters.

METHODS

We analyzed five studies on fetal ultrasound measurements using three French data sources. Two studies used second and third trimester ultrasound data from a nationwide birth cohort in 2011 (the ELFE study, N = 13 197 and N = 7747); one study used third trimester ultrasound data from on a nationwide cross-sectional study (the 2016 French National Perinatal Survey, N = 9940); and the last two studies were from the "Flash study" 2014 which prospectively collected ultrasound data from routine visits in the second and third trimesters (N = 4858 and N = 3522). For each study, we reported the percentage of measurements below the 10th percentile or above the 90th percentile, using French, Hadlock's, WHO and Intergrowth (IG) charts.

RESULTS

WHO classified 4.7% and 16.3% of fetuses as having an estimated fetal weight (EFW) <10th and >90th percentiles in the second trimester compared to 3.3% and 34.7% with IG. The percentage of fetuses in the third trimester with an EFW <10th and >90th percentiles, ranged from 9.1% to 9.4% and from 8.0% to 11.1%, respectively, for WHO, and from 3.9% to 4.1% and from 17.3% to 21.6%, respectively, for IG. The WHO and IG charts for head circumference were very similar and performed well. Compared to the WHO charts, the French and Hadlock's charts deviated more frequently from the target percentiles values for EFW and biometric measures.

CONCLUSION

It is recommended to use the WHO charts for the assessment of EFW and ultrasound biometric measurements in France (strong recommendation; low quality of evidence).

[A pragmatic comparison of fetal biometry curves]

INTRODUCTION

The fetal biometrics charts recommended in France for ultrasound screening include measurements of head circumference (HC), biparietal diameter (BIP), abdominal circumference (AC) and femur length (FL). New international growth standards have been recommended since 2022. The aim of this work is to quantitatively describe the differences between these biometric curves.

METHODS

The biometry curves from the French College for Fetal Ultrasound, OMS and INTERGROWTH-21 are pragmatically compared based on their original quantile regression equations (superposition and quantification of differences in millimeters and in proportion) for different percentiles of clinical interest.

RESULTS

Compared with the new charts, CFEF underestimates HC<-3DS and AC<10eP. The proportions of differences between the CFEF and INTERGROWTH-21 or WHO curves always remained <5%. The proportions of difference of the 3rd percentile of HC and FL, 10th and 90th percentile of AC were always lower than 2%, 2%, 5% and 4% respectively, between OMS and INTERGROWTH-21.

CONCLUSION

The switch to prescriptive standards suggests an improvement in the detection of fetuses with AC<10th percentile, an improvement in the detection of prenatal onset microcephaly, with no argument for a decrease in the detection rate of severe constitutional bone disease or modification of obstetrical guidelines.

Implications for quantifying early life growth trajectories of term-born infants using INTERGROWTH-21st newborn size standards at birth in conjunction with World Health Organization child growth standards in the postnatal period

BACKGROUND

The INTERGROWTH-21st sex and gestational age (GA) specific newborn size standards (IG-NS) are intended to complement the World Health Organization Child Growth Standards (WHO-GS), which are not GA-specific. We examined the implications of using IG-NS at birth and WHO-GS at postnatal ages in longitudinal epidemiologic studies.

OBJECTIVES

The aim of this study was to quantify the extent to which standardised measures of newborn size and growth are affected when using WHO-GS versus IG-NS at birth among term-born infants.

METHODS

Data from two prenatal trials in Bangladesh (n = 755) and The Gambia (n = 522) were used to estimate and compare size at birth and growth from birth to 3 months when using WHO-GS only ('WHO-GS') versus IG-NS at birth and WHO-GS postnatally ('IG-NS'). Mean length-for-age (LAZ), weight-for-age (WAZ) and head circumference-for-age (HCAZ), and the prevalence of undernutrition (stunting: LAZ < -2SD; underweight: WAZ < -2SD; and microcephaly: HCAZ < -2SD) were estimated overall and by GA strata [early-term (370/7 -386/7 ), full-term (390/7 -406/7 ) and late-term (410/7 -430/7 )]. We used Bland-Altman plots to compare continuous indices and Kappa statistic to compare categorical indicators.

RESULTS

At birth, mean LAZ, WAZ and HCAZ, and the prevalence of undernutrition were most similar among newborns between 39 and 40 weeks of GA when using WHO-GS versus IG-NS. However, anthropometric indices were systematically lower among early-term infants and higher among late-term infants when using WHO-GS versus IG-NS. Early-term and late-term infants demonstrated relatively faster and slower growth, respectively, when using WHO-GS versus IG-NS, with the direction and magnitude of differences varying between anthropometric indices. Individual-level differences in attained size and growth, when using WHO-GS versus IG-NS, were greater than 0.2 SD in magnitude for >60% of infants across all anthropometric indices.

CONCLUSIONS

Using IG-NS at birth with WHO-GS postnatally is acceptable for full-term infants but may give a misleading interpretation of growth trajectories among early- and late-term infants.

The choice of reference chart affects the strength of the association between malaria in pregnancy and small for gestational age: an individual participant data meta-analysis comparing the Intergrowth-21 with a Tanzanian birthweight chart

BACKGROUND

The prevalence of small for gestational age (SGA) may vary depending on the chosen weight-for-gestational-age reference chart. An individual participant data meta-analysis was conducted to assess the implications of using a local reference (STOPPAM) instead of a universal reference (Intergrowth-21) on the association between malaria in pregnancy and SGA.

METHODS

Individual participant data of 6,236 newborns were pooled from seven conveniently identified studies conducted in Tanzania and Malawi from 2003-2018 with data on malaria in pregnancy, birthweight, and ultrasound estimated gestational age. Mixed-effects regression models were used to compare the association between malaria in pregnancy and SGA when using the STOPPAM and the Intergrowth-21 references, respectively.

RESULTS

The 10th percentile for birthweights-for-gestational age was lower for STOPPAM than for Intergrowth-21, leading to a prevalence of SGA_STOPPAM of 14.2% and SGA_IG21 of 18.0%, p < 0.001. The association between malaria in pregnancy and SGA was stronger for STOPPAM (adjusted odds ratio (aOR) 1.30 [1.09-1.56], p < 0.01) than for Intergrowth-21 (aOR 1.19 [1.00-1.40], p = 0.04), particularly among paucigravidae (SGA_STOPPAM aOR 1.36 [1.09-1.71], p < 0.01 vs SGA_IG21 aOR 1.21 [0.97-1.50], p = 0.08).

CONCLUSIONS

The prevalence of SGA may be overestimated and the impact of malaria in pregnancy underestimated when using Intergrowth-21. Comparing local reference charts to global references when assessing and interpreting the impact of malaria in pregnancy may be appropriate.

[Ante- and postnatal growth charts in France - guidelines for clinical practice from the Collège national des gynécologues et obstétriciens français (CNGOF) and from the Société française de néonatologie (SFN)]

OBJECTIVE

To recommend the most appropriate biometric charts for the detection of antenatal growth abnormalities and postnatal growth surveillance.

METHODS

Elaboration of specific questions and selection of experts by the organizing committee to answer these questions; analysis of the literature by experts and drafting conclusions by assigning a recommendation (strong or weak) and a quality of evidence (high, moderate, low, very low) and for each question; all these recommendations have been subject to multidisciplinary external review (obstetrician gynecologists, pediatricians). The objective for the reviewers was to verify the completeness of the literature review, to verify the levels of evidence established and the consistency and applicability of the resulting recommendations. The overall review of the literature, quality of evidence and recommendations were revised to take into consideration comments from external reviewers.

RESULTS

Antenatally, it is recommended to use all WHO fetal growth charts for EFW and common ultrasound biometric measurements (strong recommendation; low quality of evidence). Indeed, in comparison with other prescriptive curves and descriptive curves, the WHO prescriptive charts show better performance for the screening of SGA (Small for Gestational Age) and LGA (Large for Gestational Age) with adequate proportions of fetuses screened at extreme percentiles in the French population. It also has the advantages of having EFW charts by sex and biometric parameters obtained from the same perspective cohort of women screened by qualified sonographers who measured the biometric parameters according to international standards. Postnatally, it is recommended to use the updated Fenton charts for the assessment of birth measurements and for growth monitoring in preterm infants (strong recommendation; moderate quality of evidence) and for the assessment of birth measurements in term newborn (expert opinion).

CONCLUSION

It is recommended to use WHO fetal growth charts for antenatal growth monitoring and Fenton charts for the newborn.

Which fetal growth charts should be used? A retrospective observational study in China

BACKGROUND

The fetal growth charts in widest use in China were published by Hadlock >35 years ago and were established on data from several hundred of American pregnant women. After that, >100 fetal growth charts were published around the world. We attempted to assess the impact of applying the long-standing Hadlock charts and other charts in a Chinese population and to compare their ability to predict newborn small for gestational age (SGA).

METHODS

For this retrospective observational study, we reviewed all pregnant women ( n  = 106,455) who booked prenatal care with ultrasound measurements for fetal biometry at the Shenzhen Maternity and Child Healthcare Hospital between 2012 and 2019. A fractional polynomial regression model was applied to generate Shenzhen fetal growth chart ranges for head circumference (HC), biparietal diameter (BPD), abdominal circumference (AC), and femur length (FL). The differences between Shenzhen charts and published charts were quantified by calculating the Z -score. The impact of applying these published charts was quantified by calculating the proportions of fetuses with biometric measurements below the 3rd centile of these charts. The sensitivity and area under the receiver operating characteristic curves of published charts to predict neonatal SGA (birthweight <10th centile) were assessed.

RESULTS

Following selection, 169,980 scans of fetal biometry contributed by 41,032 pregnancies with reliable gestational age were analyzed. When using Hadlock references (<3rd centile), the proportions of small heads and short femurs were as high as 8.9% and 6.6% in late gestation, respectively. The INTERGROWTH-21st standards matched those of our observed curves better than other charts, in particular for fat-free biometry (HC and FL). When using AC<10th centile, all of these references were poor at predicting neonatal SGA.

CONCLUSIONS

Applying long-standing Hadlock references could misclassify a large proportion of fetuses as SGA. INTERGROWTH-21st standard appears to be a safe option in China. For fat-based biometry, AC, a reference based on the Chinese population is needed. In addition, when applying published charts, particular care should be taken due to the discrepancy of measurement methods.

Associations of severe adverse perinatal outcomes among continuous birth weight percentiles on different birth weight charts: a secondary analysis of a cluster randomized trial

Objective

To identify neonatal risk for severe adverse perinatal outcomes across birth weight centiles in two Dutch and one international birth weight chart.

Background

Growth restricted newborns have not reached their intrinsic growth potential in utero and are at risk of perinatal morbidity and mortality. There is no golden standard for the confirmation of the diagnosis of fetal growth restriction after birth. Estimated fetal weight and birth weight below the 10^th percentile are generally used as proxy for growth restriction. The choice of birth weight chart influences the specific cut-off by which birth weight is defined as abnormal, thereby triggering clinical management. Ideally, this cut-off should discriminate appropriately between newborns at low and at high risk of severe adverse perinatal outcomes and consequently correctly inform clinical management.

Methods

This is a secondary analysis of the IUGR Risk Selection (IRIS) study. Newborns (n = 12 953) of women with a low-risk status at the start of pregnancy and that received primary antenatal care in the Netherlands were included.

We examined the distribution of severe adverse perinatal outcomes across birth weight centiles for three birth weight charts (Visser, Hoftiezer and INTERGROWTH) by categorizing birth weight centile groups and comparing the prognostic performance for severe adverse perinatal outcomes.

Severe adverse perinatal outcomes were defined as a composite of one or more of the following: perinatal death, Apgar score < 4 at 5 min, impaired consciousness, asphyxia, seizures, assisted ventilation, septicemia, meningitis, bronchopulmonary dysplasia, intraventricular hemorrhage, periventricular leukomalacia, or necrotizing enterocolitis.

Results

We found the highest rates of severe adverse perinatal outcomes among the smallest newborns (< 3^rd percentile) (6.2% for the Visser reference curve, 8.6% for the Hoftiezer chart and 12.0% for the INTERGROWTH chart). Discriminative abilities of the three birth weight charts across the entire range of birth weight centiles were poor with areas under the curve ranging from 0.57 to 0.61. Sensitivity rates of the various cut-offs were also low.

Conclusions

The clinical utility of all three charts in identifying high risk of severe adverse perinatal outcomes is poor. There is no single cut-off that discriminates clearly between newborns at low or high risk.

Trial Registration

Netherlands Trial Register NTR4367.

Registration date March 20^th, 2014.

Assessing fetal growth in Africa: Application of the international WHO and INTERGROWTH-21st standards in a Beninese pregnancy cohort

BACKGROUND

Fetal growth restriction is a major complication of pregnancy and is associated with stillbirth, infant death and child morbidity. Ultrasound monitoring of pregnancy is becoming more common in Africa for fetal growth monitoring in clinical care and research, but many countries have no national growth charts. We evaluated the new international fetal growth standards from INTERGROWTH-21st and WHO in a cohort from southern Benin.

METHODS

Repeated ultrasound and clinical data were collected in women from the preconceptional RECIPAL cohort (241 women with singleton pregnancies, 964 ultrasounds). We modelled fetal biometric parameters including abdominal circumference (AC) and estimated fetal weight (EFW) and compared centiles to INTERGROWTH-21st and WHO standards, using the Bland and Altman method to assess agreement. For EFW, we used INTERGROWTH-21st standards based on their EFW formula (IG21st) as well as a recent update using Hadlock's EFW formula (IG21hl). Proportions of fetuses with measurements under the 10th percentile were compared.

RESULTS

Maternal malaria and anaemia prevalence was 43% and 69% respectively and 11% of women were primigravid. Overall, the centiles in the RECIPAL cohort were higher than that of INTERGROWTH-21st and closer to that of WHO. Consequently, the proportion of fetuses under 10th percentile thresholds was systematically lower when applying IG21st compared to WHO standards. At 27-31 weeks and 33-38 weeks, respectively, 7.4% and 5.6% of fetuses had EFW <10th percentile using IG21hl standards versus 10.7% and 11.6% using WHO standards.

CONCLUSION

Despite high anemia and malaria prevalence in the cohort, IG21st and WHO standards did not identify higher than expected proportions of fetuses under the 10th percentiles of ultrasound parameters or EFW. The proportions of fetuses under the 10th percentile threshold for IG21st charts were particularly low, raising questions about its use to identify growth-restricted fetuses in Africa.

World Health Organization fetal growth charts applied in a French birth cohort

OBJECTIVE

To evaluate the applicability of World Health Organization (WHO) fetal growth charts for abdominal circumference (AC), femur length (FL) and estimated fetal weight (EFW) at the second and third trimester ultrasounds in a French birth cohort.

MATERIALS AND METHODS

Using the ELFE cohort of live births after 33 weeks' gestation in France in 2011, we selected 7747 singletons with fetal biometric measurements at the second (20-25 weeks) and third (30-35 weeks) trimester routine ultrasounds. We calculated proportions of fetuses <3rd and <10th percentiles and >90th and >97th percentiles for AC, FL and EFW using WHO charts and two international (Intergrowth and Hadlock) and two national (Salomon and CFEF) charts. Analyses were also carried out in a subsample of 4427 low-risk births.

RESULTS

WHO charts classified 2,3% and 8-10% of fetuses <3rd and <10th percentiles respectively, for AC and FL in the second and third trimesters and EFW in the third trimester. Similarly, about 3 and 10% of fetuses had AC, FL and EFW >97th and >90th percentile in both trimesters. Hadlock and CFEF charts also provided a good fit for third-trimester EFW <10th percentile. For most measures, Intergrowth yielded low proportions <3rd and <10th percentile, and high proportions >90th and >97th percentiles. Proportions were slightly lower for low-risk pregnancies.

CONCLUSION

WHO charts provided a good description of the distribution of French fetal biometric measures. Further research is needed to assess the impact of using WHO charts on obstetrical management and perinatal outcomes.

Should Fetal Growth Charts Be References or Standards?

BACKGROUND

Fetal growth standards (prescriptive charts derived from low-risk pregnancies) are theoretically better tools to monitor fetal growth than conventional references. We examined how modifying chart inclusion criteria influenced the resulting curves.

METHODS

We summarized estimated fetal weight (EFW) distributions from a hospital's routine 32-week ultrasound in all nonanomalous singleton fetuses (reference) and in those without maternal-fetal conditions affecting fetal growth (standard). We calculated EFWs for the 3rd, 5th, 10th, and 50th percentiles, and the proportion of fetuses each chart classified as small for gestational age.

RESULTS

Of 2309 fetuses in our reference, 690 (30%) met the standard's inclusion criteria. There were no meaningful differences between the EFW distributions of the reference and standard curves (50th percentile: 1989 g reference vs. 1968 g standard; 10th percentile: 1711 g reference vs. 1710 g standard), or the proportion of small for gestational age fetuses (both 9.9%).

CONCLUSIONS

In our study, there was little practical difference between a fetal growth reference and standard for detecting small infants.

Agreement Analysis between Sonographic Estimates and Birth Weight, by the WHO and Intergrowth-21st Tables, in Newborns of Diabetic Mothers

OBJECTIVE

 To analyze the agreement, in relation to the 90th percentile, of ultrasound measurements of abdominal circumference (AC) and estimated fetal weight (EFW), between the World Health Organization (WHO) and the International Fetal and Newborn Growth Consortium for the 21st Century (intergrowth-21st) tables, as well as regarding birth weight in fetuses/newborns of diabetic mothers.

METHODS

 Retrospective study with data from medical records of 171 diabetic pregnant women, single pregnancies, followed between January 2017 and June 2018. Abdominal circumference and EFW data at admission (from 22 weeks) and predelivery (up to 3 weeks) were analyzed. These measures were classified in relation to the 90th percentile. The Kappa coefficient was used to analyze the agreement of these ultrasound variables between the WHO and intergrowth-21st tables, as well as, by reference table, these measurements and birth weight.

RESULTS

 The WHO study reported 21.6% large-for-gestational-age (LGA) newborns while the intergrowth-21st reported 32.2%. Both tables had strong concordances in the assessment of initial AC, final AC, and initial EFW (Kappa = 0.66, 0.72 and 0.63, respectively) and almost perfect concordance in relation to final EFW (Kappa = 0.91). Regarding birth weight, the best concordances were found for initial AC (WHO: Kappa = 0.35; intergrowth-21st: Kappa = 0.42) and with the final EFW (WHO: Kappa = 0.33; intergrowth- 21st: Kappa = 0.35).

CONCLUSION

 The initial AC and final EFW were the parameters of best agreement regarding birth weight classification. The WHO and intergrowth-21st tables showed high agreement in the classification of ultrasound measurements in relation to the 90th percentile. Studies are needed to confirm whether any of these tables are superior in predicting short- and long-term negative outcomes in the LGA group.

Swedish intrauterine growth reference ranges of biometric measurements of fetal head, abdomen and femur

Ultrasonic assessment of fetal growth is an important part of obstetric care to prevent adverse pregnancy outcome. However, lack of reliable reference ranges is a major barrier for accurate interpretation of the examinations. The aim of this study was to create updated Swedish national reference ranges for intrauterine size and growth of the fetal head, abdomen and femur from gestational week 12 to 42. This prospective longitudinal multicentre study included 583 healthy pregnant women with low risk of aberrant fetal growth. Each woman was examined up to five times with ultrasound from gestational week 12 + 3 to 41 + 6. The assessed intrauterine fetal biometric measurements were biparietal diameter (outer–inner), head circumference, mean abdominal diameter, abdominal circumference and femur length. A two-level hierarchical regression model was employed to account for the individual measurements of the fetus and the number of repeated visits for measurements while accounting for the random effect of the identified parameterization of gestational age. The expected median and variance, expressed in both standard deviations and percentiles, for each individual biometric measurement was calculated. The presented national reference ranges can be used for assessment of intrauterine size and growth of the fetal head, abdomen and femur in the second and third trimester of pregnancy.

Application of new fetal growth standards in a multiethnic population

OBJECTIVES

Ultrasound assessment of fetal growth is essential to reduce adverse pregnancy outcomes. Intergrowth-21st developed international standards. Currently, we use in France chart based on Hadlock's formula. This study aims to evaluate, the impact of switching from national curves to IG-21 curves or a combination of IG-21 with Hadlock.

METHODS

The study population consisted of 3 697 singleton pregnancies with fetal biometry measured between 22 and 38 weeks of gestation. Z-scores were calculated for each biometry according to CFEF and IG-21. The estimated fetal weight and its Z-score were calculated using the Hadlock formula and IG-21 formula.

RESULTS

We observed 21% of head circumference, 9% of abdominal circumference and 7% of femoral length below the 10th centile with Intergrowth-21. Concerning estimated fetal weight, IG-21 classified 13.8% fetuses as SGA, IG-21/Hadlock 10.8% and CFEF 16.1%. Between 36 and 38 weeks of gestation, IG-21 classified more fetuses as SGA than IG-21/Hadlock and CFEF, respectively 18%, 14.1% and 13.3%.

CONCLUSION

The use of IG-21 or IG-21/Hadlock in the general population would lower the number of fetuses classified as SGA except for fetuses between 36 and 38 weeks. During this period, many decisions of induced early delivery or specific management are established to prevent adverse perinatal outcome. Those results must be supplemented by a comparison to newborns' weight.

Current use and performance of the different fetal growth charts in the Italian population

OBJECTIVES

The choice of growth charts impacts on screening, diagnosis and clinical management of fetal growth abnormalities. The objectives of the study were to evaluate: 1) the clinical practice at a national level among tertiary referral centers in the use of fetal biometric growth charts; and 2) the impact on fetal growth screening of existing national and international growth charts.

STUDY DESIGN

A questionnaire was sent to 14 Italian tertiary referral centers to explore biometric reference growth charts used in clinical practice. National and international (Intergrowth-21st and World Health Organization) fetal growth charts were tested on a large national cohort of low risk women with singleton uneventful pregnancy derived from a retrospective cross-sectional multicenter study (21 centers). The percentage of fetuses with biometric measurements below and above the 10th and 90th percentile for each biometric parameter and gestational week were calculated for each growth chart. The percentile curves of the study population were calculated by non-linear quantile regressions.

RESULTS

Twelve Italian centers (86 %) answered to the questionnaire showing a wide discrepancy in the use of growth charts for fetal biometry. The cohort included 7347 pregnant women. By applying Intergrowth-21st growth charts the percentage of fetuses with head circumference, abdominal circumference and femur length below the 10th centile was 3.9 %, 3.6 % and 2.3 %, and above the 90th centile 29.9 %, 32.5 % and 46 %, respectively. The percentages for the World Health Organization growth charts for head and abdominal circumferences and femur length were: below the 10th centile 6.3 %, 7.2 % and 5.3 %, and above 90th centile 22.8 %, 21.3 % and 31.9 %, respectively.

CONCLUSIONS

The wide discrepancy in clinical use of fetal growth charts in Italian centers warrants the adoption of an uniform set of charts. Our data suggest that immediate application into clinical practice of international growth charts might result into an under-diagnosis of small for gestational age fetuses and, especially, in an over-diagnosis of large for gestational age fetuses with major consequences for clinical practice. On these grounds, there is an urgent need for a nationwide study for the prospective evaluation of international growth charts and, if needed, the construction and adoption of methodologically robust national growth charts.

Fetal biometry assessment with Intergrowth 21st's and Salomon's equations in rural Burkina Faso

Background

Ultrasound scanning during the 2nd or the 3rd trimester of pregnancy for fetal size disturbances screening is heavily dependent of the choice of the reference chart. This study aimed to assess the agreement of Salomon and the Intergrowth 21st equations in evaluating fetal biometric measurements in a rural area of Burkina Faso, and to measure the effect of changing a reference chart.

Methods

Data collected in Nazoanga, Burkina Faso, between October 2010 and October 2012, during a clinical trial evaluating the safety and efficacy of several antimalarial treatments in pregnant women were analyzed. We included singleton pregnancies at 16–36 weeks gestation as determined by ultrasound measurements of fetal bi-parietal diameter (BPD), head circumference (HC), abdominal circumference (AC) and femur length (FL). Expected mean and standard deviation at a given gestational age was computed using equations from Salomon references and using Intergrowth 21st standard. Then, z-scores were calculated and used subsequently to compare Salomon references with Intergrowth 21st standards.

Results

The analysis included 276 singleton pregnancies.

Agreement was poor except for HC: mean difference − 0.01, limits of agreement − 0.60 and 0.59. When AC was used as a surrogate of fetal size, switching from the reference of Salomon to the standards of Intergrowth 21st increased ten times the proportion of fetuses above the 90th percentile: 2.9 and 31.2%, respectively.

Mean differences were larger in the third trimester than in the second trimester. However, agreement remained good for HC in both trimesters.

Difference in the proportion of AC measurements above the 90th percentile using Salomon and Intergrowth 21st equations was greater in the second trimester (2.6 and 36.3%, respectively) than in the third trimester (3.5 and 19.8%, respectively). The greatest difference between the two charts was observed in the number of FL measurements classified as large in the second trimester (6.8 and 54.2%, using Salomon and Intergrowth 21st equations, respectively).

Conclusion

The agreement between Intergrowth 21st and Salomon equations is poor apart from HC. This would imply different clinical decision regarding the management of the pregnancy.

Offspring birthweight and placental weight in immigrant women from conflict-zone countries; does length of residence in the host country matter? A population study in Norway

INTRODUCTION

We aimed to estimate differences in offspring birthweight and placental weight between Norwegian women and immigrants in Norway from countries with armed conflicts. We also studied whether length of residence in Norway was associated with offspring birthweight and placental weight.

MATERIAL AND METHODS

We included in our study all singleton births in Norway at gestational week 28 or beyond during the years 1999-2014, to mothers who were born in Somalia, Afghanistan, Iraq (total immigrants n = 18 817), or Norway (n = 668 439). Data were obtained from The Medical Birth Registry of Norway and the Central Person Registry of Norway. We estimated the differences between Norwegian and immigrant women in mean offspring birthweight and mean placental weight by applying linear regression analyses. Adjustments were made for maternal age, parity, year of delivery, gestational age at delivery, preeclampsia, and diabetes.

RESULTS

The immigrant women had 206 g (95% CI 199 to 213 g) lower mean offspring birthweight and 16 g (95% CI 14 to 18 g) lower mean placental weight than Norwegian women. Immigrant women with ≥5 years of residence in Norway had higher offspring birthweight (40 g) and higher placental weight (17 g) than immigrant women with <5 years of residence.

CONCLUSIONS

Immigrant mothers from Somalia, Afghanistan, and Iraq gave birth to infants and placentas with lower weight than Norwegian women. However, the difference between Norwegian women and immigrant women was reduced by length of residence in Norway.

The French Pregnancy Cohort: Medication use during pregnancy in the French population

Purpose

We described the medication use during pregnancy in the French population using the French Pregnancy Cohort (FPC).

Methods

The FPC was built with the sampling of all pregnant women included in the French Echantillon généraliste des bénéficiaires (EGB), which is a 1/97^th representative sample of the population covered by the French health insurance. The EGB includes anonymized information on the socio-demographic and medical characteristics of beneficiaries, and the health care services they have received such as diagnoses and procedure codes as well as data on filled reimbursed medication; EGB also includes data on hospital stays in all public and private French health facilities. Each filled prescription record contains information on drug brand and generic names, date of prescription and date of dispensing, quantity dispensed, mode of administration, duration of prescription, dosage, and prescribing physician specialty. FPC includes data on all pregnancies of women in the EGB (2010–2013). Date of entry in the FPC is the first day of pregnancy regardless of pregnancy outcome (spontaneous abortions or planned abortions (with or without medical reasons), deliveries), and data on women are collected retrospectively for a period of one year before pregnancy, and prospectively during pregnancy, and up to one year after delivery. The prevalence of prescribed medications before, during and after pregnancy was compared; comparison was also done between trimesters. Pregnancy outcomes are described and include spontaneous and planned abortions, livebirths, and stillbirths.

Results

FPC includes data on 36,065 pregnancies. Among them, 27,253 (75.6%) resulted in a delivery including 201 stillbirths (0.7%). The total number of spontaneous abortions was 6,718 (18.6%), and planned abortions 2,094 (5.8%). The prevalence of filled medication use was 91.1%, 89.9%, and 95.6% before, during and after pregnancy, respectively. Although there was a statistically significant decrease in the proportion of use once the pregnancy was diagnosed (first trimester exposure, 76.4% vs. exposure in the year prior to pregnancy, 91.1% (p < .01)), post-pregnancy medication use was above the pre-pregnancy level (95.6%). Maternal depression was the most prevalent comorbidity during pregnancy (20%), and post-partum depression was higher in those who delivered a stillborn infant (38.8%) as well as in those with a spontaneous (19.5%) or planned abortion (22.4%) compared to those with a liveborn (12.0%).

Conclusion

FPC is an excellent tool for the study of the risk and benefit of drug use during the perinatal period. FPC has the advantage of including a representative sample of French pregnant women, and study medications only available in France in addition to others available worldwide.