PI-094 - ANALYZING AND INTEGRATING POSTPARTUM PHYSIOLOGICAL CHANGES IN LACTATING WOMEN.

N. Deferm¹, J. Dinh², A. Pansari¹, M. Jamei¹, K. Abduljalil¹; ¹Certara, Sheffield, England, United Kingdom, ²Certara UK, Sheffield, England, United Kingdom.

Background: Many postpartum (PP) women require medication, but limited drug safety data during lactation often leads to delayed treatment or breastfeeding cessation. Various publications have documented the physiological changes that occur in women and their breast milk during the PP period. By integrating this information, we can better understand how these changes individually and collectively affect pharmacotherapy during lactation. This study aims to collect and quantify these physiological changes throughout the PP period.

Methods: A PubMed search was conducted to gather data on various PP physiological parameters. Studies were included for analysis if they met the following criteria: (1) healthy breastfeeding women, (2) predominantly Caucasian adults, (3) no medication use during or after pregnancy, (4) uncomplicated pregnancies, and (5) data for full-term infants. The data were analyzed using Microsoft Excel, and functions were fitted to the observed data using postpartum age as a regressor. Weighted least squares regression was generally used, with each data point weighted by the number of study subjects. Functions were selected based on visual inspection and numerical diagnostics.

Results: The literature search identified 214 studies, providing 34577 data points from 19316 postpartum women, with data collected from one day to 12 months PP. The parameters collected included breast volume, plasma volume, milk volume, milk pH, milk fat, haematocrit, human serum albumin and alpha-1-acid glycoprotein levels, glomerular filtration rate, cardiac output and infant milk intake. Most parameters returned to pre-pregnancy levels within 12 months, except for breast volume, which remained elevated. The functions used effectively described the observed data, as confirmed by predicted versus observed plots from simulations of 5000 postpartum women, which also accurately captured the observed variability.

Conclusion: Eleven functions describing changes in physiological parameters during the PP period were derived from a substantial dataset. These functions accurately represented the observed data, indicating that these new algorithms can help enhance the predictive capabilities of pharmacokinetic models and study designs during lactation.