A prospective observational study of early fetal growth velocity and its association with birth weight, gestational age at delivery, preeclampsia, and perinatal mortality

Prenatal exposure to fine particulate matter and fetal growth: a cohort study from a velocity perspective

BACKGROUND

Reduced growth velocity before birth increases the risk of adverse health outcomes in adult life. However, until recently, there has been a lack of studies demonstrating the impact of prenatal PM_2.5 exposure on fetal growth velocity.

METHODS

The current study was embedded in a previous cohort built between January 1, 2014, and April 30, 2015, in Shanghai First Maternity and Infant Hospital, China, in 6129 eligible singleton pregnancies. The PM_2.5 concentration was estimated by an inverse distance weighted method according to the residential addresses of the participants. Repeated fetal biometry measurements, including head circumference (HC), abdominal circumference (AC), femur length (FL), and biparietal diameter (BPD), were measured through ultrasound between 14 and 41 gestational weeks. A principal component analysis through conditional expectation for sparse longitudinal data was used to estimate the corresponding velocities.

RESULTS

A total of 22782 ultrasound measurements were conducted among 6129 participants with a median of 2 and a maximum of 9 measurements. With each 10 μg/m³ increase in cumulative PM_2.5 exposure, the velocity of HC, AC FL and BPD decreased by 0.12 mm/week, 0.17 mm/week, 0.02 mm/week and 0.02 mm/week, respectively, on average. The results of the Generalized Functional Concurrent Model showed that the velocity decreased significantly with PM_2.5 exposure between 22 and 32 gestational weeks, which might be the potential sensitive exposure window.

CONCLUSIONS

There are negative associations between prenatal exposure to PM_2.5 and fetal growth velocity, and the late second trimester and early third trimester might be the potential sensitive window.

Preliminary analysis of in utero low-level arsenic exposure and fetal growth using biometric measurements extracted from fetal ultrasound reports

BACKGROUND

Early life exposure to arsenic is associated with decreased birth weight in highly exposed populations but little is known about effects of low-level arsenic exposure on growth in utero.

METHODS

Using a sample of 272 pregnancies from New Hampshire we obtained biometric measurements directly from fetal ultrasound reports commonly found in electronic medical records. We used information extraction methods to develop and validate an automated approach for mining biometric measurements from the text of clinical reports. As a preliminary analysis, we examined associations between in utero low-level arsenic exposure (as measured by maternal urinary arsenic concentration) and fetal growth measures (converted to Z-scores based on reference populations for estimated fetal weight, head, and other body measures) at approximately 18 weeks of gestation.

RESULTS

In a preliminary cross-sectional analysis of 223 out of 272 pregnancies, maternal urinary arsenic concentration (excluding arsenobetaine) was associated with a reduction in head circumference Z-score (Spearman correlation coefficient, rs = -0.08, p-value = 0.21) and a stronger association was observed among female fetuses at approximately 18 weeks of gestation (rs = - 0.21, p-value < 0.05). Although, associations were attenuated in adjusted analyses - among female fetuses a 1 μg/L increase in maternal urinary arsenic concentration was associated with a decrease of 0.047 (95% CI: -0.115, 0.021) in head circumference and 0.072 (95% CI: -0.151, 0.007) decrease in biparietal head diameter Z-score.

CONCLUSIONS

Our study demonstrates that useful data can be extracted directly from electronic medical records for epidemiologic research. We also found evidence that exposure to low-level arsenic may be associated with reduced head circumference in a sex dependent manner that warrants further investigation.