University of São Paulo: Research shows how each day in the womb impacts the baby’s development

Brazil has one of the largest numbers of early deliveries due to previously scheduled cesarean sections and inductions, resulting in shortened pregnancy. This practice has negative consequences for both the baby and the mother, whether in the short, medium or long term. With this scenario in mind, a research group coordinated by Simone Diniz, a professor at the Faculty of Public Health (FSP) at USP, created a new measure to examine maternal and child health outcomes.

From the study Potential Days of Pregnancy Missed (DPGP): an innovative measure of gestational age (GA) to assess maternal and child health interventions and outcomes , researchers support the understanding that each day of pregnancy is less than 40 weeks ( or 280 days) complete, negatively impacts the health of babies.

The new variable, simple and with great explanatory potential, was developed by counting the days left between the day of birth and the average duration of pregnancy, which is 280 days (DPGP = IG – 280 days). The indicator can be used as a predictor variable or as a dependent variable to build national and international cohorts and intervention studies, say the researchers.

“As far as we know, this is the first Brazilian study that analyzes gestational age in days during the term period to assess its impacts on the health of babies and mothers, even considering that this data is available at least for part of the Information System’s base. about Born Alive (Sinasc) since 2011,” says teacher Simone.

Based on the results, which are presented in detail below, the researchers proposed to the Ministry of Health a small change in fields 31/32 of the Birth Certificate and in SINASC to include the Gestational Age (GA) in days, based on the date of the last menstruation (LMP); on ultrasonography (US) with GI, adding the respective date of the 1st exam; and physical examination (done at birth).

“With these three measures, it is possible to build curves to compare and complement the accuracy of the DPGP, even in women without LMP or US, and calculate the under and overestimation of GI and its effects”, adds the professor.

Shortening pregnancy and replacing labor brings complications to the baby’s health

According to Simone, today there is a greater concern that babies reach the maximum of their physiological maturity , that is, their readiness for birth. With this, there are more and more changes in the classification of that long period of 35 days (called term), to increase the precision of the analysis on this fetal maturation.

The literature considers that the so-called “at term” pregnancy (between 37 and 42 weeks) can be subdivided into three phases: the early term (between 37 and 38 weeks and six days), the full term (39 to 40 weeks and six days ) and the late term (41 to 42 weeks). Another way to look at these cycles is to simply rate them by weeks.

Professor Simone Diniz draws attention to the fact that the period “at term” has been treated as a homogeneous category, believing that births in this interval could be caused safely and without additional risks. But not quite. This is because babies born with an incomplete gestational age between 37 and 39 weeks “have characteristics very similar to those born preterm, that is, with less than 37 weeks”, explains teacher Simone Diniz.

“Shortening the length of pregnancy brings greater complications and even more chances of death. In the short term, we may have events such as a greater number of newborns hospitalized in ICUs, jaundice, changes in blood glucose and breastfeeding difficulties. In the long term, we have a greater impact on cognitive development, attention deficit situations and greater risk factors for various chronic diseases that may arise throughout life”, says the professor.

One of the explanations for such consequences is that not only the shortening of the gestational period, but also the replacement of natural labor by interventions such as cesarean, “burn out” crucial stages for development.

“The labor process shows gestational maturity and readiness for this dramatic transition from fetal to neonatal life. Labor signals the body an epigenetic change (changes in phenotype, which are perpetuated in cell divisions, without altering the DNA sequence) necessary to activate or deactivate genes from one step to the next”, explains Simone.

Research also shows that babies born vaginally have the opportunity to get in touch with the mother’s vaginal microbiome, which makes seeding the baby’s microbiome more appropriate. On the other hand, those born by cesarean first come into contact with hospital bacteria, he says.

“There are robust studies showing that those born by cesarean have an inflammatory metabolic profile and are more vulnerable to chronic diseases in general. Among the most common inflammatory diseases are asthma, eczema, diabetes mellitus , and greater chances of developing certain cancers.”

The project had more than 30 researchers and consultants from more than ten different institutions. In partnership with Sinasc of the Municipal Health Department (SMS) of the Municipality of São Paulo (MSP), data from 1,525,759 live births in the municipality (2012-2019) were analyzed, with 504,302 with GA in days, and at the national level , 8,854,727 live births, 3,329,339 with GI in days. Both sets of data were linked to the Mortality Information System (SIM) and, at the municipal level, also to the Hospital Admission System (SIH). Records without GI information in days were analyzed in the gestational weeks and, alternatively, missing data imputation models were developed for the municipal database.

The researchers used machine learning capabilities to build predictive models and developed an application to correct data where it is incomplete. They also provided service training to improve data quality. The project was approved in the so-called Data Science Approaches to Improve Maternal and Child Health in Brazil , being jointly funded by CNPq and the Bill and Melinda Gates Foundation.

Main results

During the gestation period, at national and municipal level, all models showed significant differences in neonatal Hazard Ratio mortality by DPGP, confirming that “every day counts”;
C-sections for rich and poor women differ in GI, obstetric and clinical attributes, with the poorest having worse outcomes, reflecting differences in access to technology to offset the effects of DPGPs (eg admission to the NICU);
Women with higher education, living in areas with a higher HDI, tend to have more premature births, and lose more days in the term period. In all analyses, an “expected disparity reversal” was found in the GI, as in previous decades the opposite was expected;
For women with term pregnancies, the risk of long hospital stay and hospital readmission is greater in women with shorter pregnancies;
Robson’s group analysis is useful not only to indicate the excess of cesarean sections and calculate the loss of days per group, but also to study the excessive use of induction to labor. The quality of information about induction (eg, distinguishing “induction” from “conduction”) is variable in general low;
The data literacy of health professionals and managers is variable and tends to be low, so the group produced a website , the Conversando sobre podcast and a YouTube channel with videos about the research. In addition, it organized the course Reading, Understanding and Presenting Data in Public Health (Data literacy) – LEADSP, given in February 2021 during the Summer Courses program at FSP-USP. An app on mortality and GI trends was also developed;
Suggestion of a small and promising change in fields 31/32 of the Live Birth Certificate and in SINASC , to include GI in days, based on the last menstrual period (LMP), ultrasound (US) with GI, adding the respective date of the 1st exam ; and physical examination (done at birth). With three measures, it would be possible to build curves to compare and complement the accuracy of the DPGP, even in women without LMP or US, and calculate the under and overestimation of GI and its effects;
The covid-19 pandemic added variable interruptions to perinatal care, such as suspension of prenatal consultations, reduction and displacement of referral obstetric beds, and risks of coronavirus infection in women and families at general hospital admission. These 2020 trends are being mapped;
Creation of databases from municipal and national databases, with gestational age in days and weeks, with and without imputation, in addition to the production of an ontology of Sinasc-SIM bases and links, which will be made available for research and teaching purposes;
Publication of an article in the Revista de Saúde Pública .