Subhourly variability of circulating third trimester maternal steroid concentrations as a source of sampling error

Area of Science:

• Reproductive endocrinology
• Maternal-fetal medicine
• Clinical biochemistry

Background:

• Accurate monitoring of steroid hormone levels is crucial in late pregnancy.
• Individual variability in hormone concentrations can complicate interpretation.
• Previous studies have not fully characterized short-term fluctuations in key pregnancy steroids.

Purpose of the Study:

• To assess the variability of key steroid hormones in plasma during the third trimester of pregnancy.
• To determine if short-interval blood sampling (5 vs. 15 minutes) affects the variability of hormone measurements.
• To establish optimal sampling strategies for accurate steroid hormone assessment in pregnant individuals.

Main Methods:

• Collected serial plasma samples from five healthy pregnant women in their third trimester.
• Measured concentrations of estradiol (E2), estriol, progesterone, 16 alpha-hydroxyprogesterone, and 17 alpha-hydroxyprogesterone (17P).
• Analyzed data using statistical methods to compare variability between different sampling intervals and determine confidence intervals.

Main Results:

• Significant inter-individual variability observed for all measured steroids, with single samples showing wide deviations from the mean.
• No significant difference in mean percentage coefficients of variation between 5-min and 15-min sampling sequences.
• Increasing the number of samples significantly reduces the confidence interval width for hormone concentrations.

Conclusions:

• Multiple plasma sampling and pooling are essential for accurate steroid concentration studies in late pregnancy.
• Short-interval sampling frequency (5 vs. 15 min) does not significantly impact the variability of these hormone measurements.
• The study highlights the need for robust sampling protocols to account for inherent steroid variability in pregnant individuals.