Fetal Growth and Development: The Generation R Study

The importance of the female womb and the mysterious processes that take place in the uterus before birth caused it to be a sacred symbol from ancient history onwards 1. Despite this ancient general acknowledgement of the importance of fetal growth and development for human existence on earth, the only thing, however, that was generally known about pregnancy was that it lasted circa 9 lunar months. -A concept that hasn’t changed considerably though- It wasn’t until the 20th century that science enabled unravelling some of the mysteries of pregnancy. In 1968, still little was known about human fetal development. Kloosterman, a Dutch professor in obstetrics, described knowledge of that time in the following way: ”How intrauterine growth processes during a normal pregnancy evolve and what regulates these processes in humans is practically unknown. This especially involves humans for the developing human conceptus is hardly accessible for observation. Fact is that fetal growth velocity diff ers and that it is malpractice to use birth weight as a measure for maturity at birth. An early born giant and a late born dwarf with a similar birth weight can diff er largely in maturity and development.

Fetal hemodynamic adaptive changes related to intrauterine growth - The generation R study

Background - It has been suggested that an adverse fetal environment increases susceptibility to hypertension and cardiovascular disease in adult life. This increased risk may result from suboptimal development of the heart and main arteries in utero and from adaptive cardiovascular changes in conditions of reduced fetal growth. The aim of the present study was to evaluate whether reduced fetal growth is associated with fetal circulatory changes and cardiac dysfunction. Methods and Results - This study was embedded in a population-based, prospective cohort study starting in early fetal life. Fetal growth characteristics and fetal circulation variables were assessed with ultrasound and Doppler examinations in 1215 healthy women. The fetal circulation was examined in relation to estimated fetal weight. Higher placental resistance indices were strongly associated with decreased fetal growth. Cerebral resistance showed a gradual decline with reduced fetal growth. Cardiac output, peak systolic velocity of the outflow tracts, and cardiac compliance showed a gradual reduction with diminished fetal growth, whereas intraventricular pressure gradually increased. Conclusions - Decreased fetal growth is associated with adaptive fetal cardiovascular changes. Cardiac remodeling and cardiac output changes are consistent with a gradual increase in afterload and compromised arterial compliance in conditions of decreased fetal growth. These changes have already begun to occur before the stage of clinically apparent fetal growth restriction and may contribute to the increased risk of cardiovascular disease in later life

Intra- and interobserver reproducibility study of early fetal growth parameters

Objective To assess the intra- and interobserver reproducibility of fetal biometry measurements by transabdominal ultrasound in early pregnancy. Methods The study consisted of 21 singleton pregnancies with a gestational age between 9 and 14 weeks. Intraclass correlation coefficients (ICCs) and coefficients of variation (CVs) were calculated. Bland and Altman plots were computed to analyze agreement for measurements between and among observers. Limits of agreement +/- 2 SD for the differences in fetal biometry measurements in proportions of the mean of the measurements were derived. Results High intra- and interobserver ICCs were found, ranging from 0.998, crown-rump length (CRL) to 0.982, femur length (FL) and CVs ranging from 1.4% (CRL) to 5.9% (FL). Limits of agreement in the Bland and Altman plots ranged from -2.7 to 2.3% (CRL) difference from the mean to -13 to 23% (FL) difference. Agreement for fetal biometry increased with fetal size. Conclusions This study demonstrated good reproducibility of most measurements of fetal biometry in early pregnancy by abdominal ultrasound. CRL and biparietal diameter (BPD) showed high reproducibility and agreement, and head circumference (HC) to a lesser extend, from 9 weeks of gestational age onwards. abdominal circumference (AC) is only reliable from circa I I weeks onwards. FL has a poor reproducibility before 14 weeks of gestational age. Copyright (C) 2008 John Wiley & Sons, Ltd

Sex-specific differences in fetal and infant growth patterns: A prospective population-based cohort study

textabstractBackground: The objective of this study was to assess whether sex-specific differences in fetal and infant growth exist. Methods: This study was embedded in the Generation R Study, a population-based prospective birth cohort. In total, 8556 live singleton births were included. Fetal growth was assessed by ultrasound. During the first trimester, crown-rump-length (CRL) was measured. In the second and third trimester of pregnancy head circumference (HC), abdominal circumference (AC) and femur length (FL) were assessed. Information on infant growth during the first 2 years of life was obtained from Community Health Centers and included HC, body weight and length. Results: In the first trimester, male CRL was larger than female CRL (0.12 SD [95% CI 0.03,0.22]). From the second trimester onwards, HC and AC were larger in males than in females (0.30 SD [95% CI 0.26,0.34] and 0.09 SD [95% CI 0.05,0.014], respectively). However, FL in males was smaller compared to female fetuses (0.21 SD [95% CI 0.17,0.26]). Repeated measurement analyses showed a different prenatal as well as postnatal HC growth pattern between males and females. A different pattern in body weight was observed with a higher body weight in males until the age of 12 months where after females have a higher body weight. Conclusions: Sex affects both fetal as well as infant growth. Besides body size, also body proportions differ between males and females with different growth patterns. This sexual dimorphism might arise from differences in fetal programming with sex specific health differences as a consequence in later life