A customised fetal growth and birthweight standard for Qatar: a population-based cohort study.

OBJECTIVES: Customized birthweight centiles have improved the detection of small for gestational age (SGA) and large for gestational age (LGA) babies compared to existing population standards. This study used perinatal registry data to derive coefficients for developing customized growth charts for Qatar. METHODS: The PEARL registry data on women delivering in Qatar (2017-2018) was used to develop a multivariable linear regression model predicting optimal birthweight. Physiological variables included gestational age, maternal height, weight, ethnicity, parity, and sex of the baby. Pathological variables such as hypertension, preexisting and gestational diabetes and smoking were calculated and excluded to derive the optimal weight at term. RESULTS: The regression model found a term optimal birthweight of 3,235 g for a Qatari nationality mother with median height (159 cm), booking weight (72 kg), parity (1) and gestation at birth (276 days) at the end of an uncomplicated pregnancy. Constitutional coefficients significantly affecting birthweight were gestational age, height, weight, and parity. The main pathological factors were preexisting diabetes (increase by +175.7 g) and smoking (decrease by -190.9 g). The SGA and LGA rates in the entire cohort after applying the population-specific customized centiles were 11.1 and 12.2 %, respectively (contrasting with the Hadlock standard: SGA-26.3 % and LGA-1.8 %, and Fenton standard: SGA-12.9 % and LGA-4.0 %). CONCLUSIONS: Constitutional and pathological variations in fetal growth and birthweight apply in the maternity population in Qatar and have been quantified to allow the generation of customised charts for better identification of pregnancies with abnormal growth. Currently in-use population standards may misdiagnose many SGA and LGA babies.

Customised birthweight standard for a Slovenian population.

Objective To produce a customised birthweight standard for Slovenia. Methods This retrospective study used a cohort from the National Perinatal Information System of Slovenia (NPIS). Prospectively collected information from pregnancies delivered in all of Slovenia's 14 maternal hospitals between 1st January 2003 and 31st December 2012 was included. Coefficients were derived using a backward stepwise multiple regression technique. Results A total of 126,627 consecutive deliveries with complete data were included in the multivariable analysis. Maternal height, weight in early pregnancy and parity as well as the baby's sex were identified as physiological variables, with coefficients comparable to findings in other countries. The expected 280-day birthweight, free from pathological influences, of a standard size mother (height 163 cm, weight 64 kg) in her first pregnancy was 3451.3 g. Pathological influences on birthweight within this population included low and high maternal age, low and high body mass index (BMI), smoking, pre-existing and gestational diabetes and pre-existing and gestational hypertension. Conclusion The analysis confirmed the main physiological variables that affect birthweight in studies from other countries, and was able to quantify additional pathological factors of maternal age and gestational diabetes. Development of a country-specific customised birthweight standard will aid clinicians in Slovenia with the distinction between normal and abnormal small-for-gestational age (SGA) fetuses, thus avoiding unnecessary interventions and improving identification of at risk pregnancies, and long-term outcomes for infants.

Maternal and fetal risk factors for stillbirth: population based study.

OBJECTIVE: To assess the main risk factors associated with stillbirth in a multiethnic English maternity population. DESIGN: Cohort study. SETTING: National Health Service region in England. POPULATION: 92,218 normally formed singletons including 389 stillbirths from 24 weeks of gestation, delivered during 2009-11. MAIN OUTCOME MEASURE: Risk of stillbirth. RESULTS: Multivariable analysis identified a significant risk of stillbirth for parity (para 0 and para ≥ 3), ethnicity (African, African-Caribbean, Indian, and Pakistani), maternal obesity (body mass index ≥ 30), smoking, pre-existing diabetes, and history of mental health problems, antepartum haemorrhage, and fetal growth restriction (birth weight below 10th customised birthweight centile). As potentially modifiable risk factors, maternal obesity, smoking in pregnancy, and fetal growth restriction together accounted for 56.1% of the stillbirths. Presence of fetal growth restriction constituted the highest risk, and this applied to pregnancies where mothers did not smoke (adjusted relative risk 7.8, 95% confidence interval 6.6 to 10.9), did smoke (5.7, 3.6 to 10.9), and were exposed to passive smoke only (10.0, 6.6 to 15.8). Fetal growth restriction also had the largest population attributable risk for stillbirth and was fivefold greater if it was not detected antenatally than when it was (32.0% v 6.2%). In total, 195 of the 389 stillbirths in this cohort had fetal growth restriction, but in 160 (82%) it had not been detected antenatally. Antenatal recognition of fetal growth restriction resulted in delivery 10 days earlier than when it was not detected: median 270 (interquartile range 261-279) days v 280 (interquartile range 273-287) days. The overall stillbirth rate (per 1000 births) was 4.2, but only 2.4 in pregnancies without fetal growth restriction, increasing to 9.7 with antenatally detected fetal growth restriction and 19.8 when it was not detected. CONCLUSION: Most normally formed singleton stillbirths are potentially avoidable. The single largest risk factor is unrecognised fetal growth restriction, and preventive strategies need to focus on improving antenatal detection.

The customized fetal growth potential: a standard for Ireland.

OBJECTIVE: To identify maternal and pregnancy-related physiological and pathological variables associated with fetal growth and birthweight in Ireland and to develop customized birthweight centile charts for the Irish population that will aid in appropriate identification and selection of growth-restricted fetuses requiring increased antenatal surveillance. STUDY DESIGN: Prospectively collected outcome data of 11,973 consecutive ultrasound-dated singleton pregnancies between 2008 and 2009 from six maternity units in Ireland (Dublin, Galway, Limerick and Belfast) were included for analysis. Maternal weight and height at booking, parity and ethnicity were recorded and combined with birthweight, fetal gender and pregnancy outcomes. Coefficients were derived by backward multiple regression using a stepwise backward elimination approach. RESULTS: A total of 11,973 ultrasound-dated singleton pregnancies were included in the analysis. Over 90% of women (n=10,850) were of Irish or European descent, 3.4% (n=407) were African or African Caribbean, 1.7% (n=208) were Indian; 42.2% (n=5057) were nulliparous, 32.8% (n=3923) had one previous delivery after 24 weeks' gestation, 15.6% (n=1872) had two previous deliveries and 9.4% (n=1121) had three or more previous deliveries. Mean term birthweight for a standard Irish mother was 3491 grams. Babies of all other ethnic origins were smaller than their Irish counterparts. African Caribbean, Bangladeshi, Indian and Pakistani babies were on average 237 g, 196 g, 181 g and 181 g lighter, respectively, when compared to the average Irish offspring. Pathological factors significantly affecting term birthweight were pre-gestational diabetes (+137 g; p<0.001), smoking (-225 g; p<0.001), pregnancy-induced hypertension (-37.6g; p=0.009) and maternal obesity (-41.6g; p=0.012). CONCLUSION: Birthweight in this Irish maternity population is subject to similar influences to those observed in studies from the UK, Sweden, USA and Australasia. The derived coefficients can be used for customized assessment of fetal growth potential in Ireland. The implementation of these customized centile charts and their free online availability will aid clinicians in Ireland in the interpretation of fetal weight estimation.

A customized standard to assess fetal growth in a US population.

OBJECTIVE: The objective of the study was to assess the factors that affect fetal growth and birthweight, and to derive coefficients for a customized growth chart applicable in an American population. STUDY DESIGN: This was a prospective cohort study of 35,235 pregnancies. Coefficients for physiological and pathological variables were derived by backward multiple regression. RESULTS: The expected birthweight at 40.0 weeks for a standard-size primiparous mother of European origin in an uncomplicated pregnancy was 3453.4 g, very similar to the standardized birthweight observed in other populations. Physiological coefficients were derived for maternal height, weight, parity, ethnic origin, and sex of the baby. Smoking, history of preterm delivery, and hypertensive diseases in the current pregnancy all had negative effects on birthweight, whereas babies of diabetic mothers weighed more. Low as well as high body mass index was associated with birthweight deficit at term. CONCLUSION: Coefficients that allow determination of the customized growth potential, individually adjusted and excluding known pathological factors, have been derived. Babies of obese mothers have an increased risk of not reaching their fetal growth potential.

Prematurity and fetal growth restriction.

Assessment of the growth status of the fetus and neonate is an essential component of perinatal care. It requires a distinction to be made between physiological and pathological factors, and the prediction of the optimal growth that a baby can achieve in a normal, uncomplicated pregnancy. Such an individually customised standard can now be easily calculated by computer: it needs to be accurately dated, individually adjusted for physiological characteristics, exclude pathological factors such as smoking, and be based on a fetal weight trajectory derived from normal term pregnancies. Application of a customised standard to calculate the growth status of preterm babies gives us freshly insights into the causes of prematurity. Fetal growth restriction is seen as a strongly associated factor, which is often present before the onset of spontaneous preterm labour. This raises the question whether, in many instances, the initiation of parturition should be seen as a fetal adaptive response aimed at escaping an unfavourable intrauterine environment. These concepts have implications for the understanding of the pathophysiology of preterm labour, as well as its clinical management.

Restricted fetal growth in sudden intrauterine unexplained death.

BACKGROUND: Unexplained antepartum stillbirth is a common cause of perinatal death, and identifying the fetus at risk is a challenge for obstetric practice. Intrauterine growth restriction (IUGR) is associated with a variety of adverse perinatal outcomes, but reports on its impact on unexplained stillbirths by population-based birthweight standards have been varying, including both unexplained and unexplored stillbirths. AIM: We have studied IUGR, assessed by individually adjusted fetal weight standards, in antepartum deaths that remained unexplained despite thorough postmortem investigations. METHODS: Antenatal health cards from a complete population-based 10-year material of 76 validated sudden intrauterine unexplained deaths were compared to those of 582 randomly selected liveborn controls. Birthweight <10th percentile of the individualized standard adjusted for gestational age, maternal height, weight, parity, ethnicity, and fetal gender was defined as growth restriction. RESULTS: 52% of unexplained stillbirths were growth restricted, with a mean gestational age at death of 35.1 weeks. Suboptimal growth was the most important fetal determinant for sudden intrauterine unexplained death (odds ratio 7.0, 95% confidence interval 3.3-15.1). Concurrent maternal overweight or obesity, high age, and low education further increase the risk. Overweight and obesity increase the risk irrespective of fetal growth, and while high maternal age increases the risk of the normal weight fetus, it is not associated to growth restriction as a precursor of sudden intrauterine unexplained death. CONCLUSIONS: IUGR is an important risk factor of sudden intrauterine unexplained death, and this should be excluded in pregnancies with any other risk factor for sudden intrauterine unexplained death.