Study paints comprehensive picture of changes caused by pregnancy

A new study paints an unprecedented picture of the changes a woman’s body undergoes during and after pregnancy, revealing long-term impacts on organs such as the liver and kidneys.

The data for this study comes from 76 laboratory tests performed during more than 300,000 pregnancies, representing a total of some 44 million measurements. Each test was assessed weekly, from 20 weeks before conception to 80 weeks after delivery.

These 76 tests documented, among other things, the impact of pregnancy on the liver, kidneys, blood, muscles, bones, and immune system.

“There is much less monitoring and attention paid to the postpartum period for women,” commented Dr. Anne-Maude Morency, an obstetrician-gynecologist at the McGill University Health Centre.

“At that point, the newborns have their follow-up and all that, but it’s as if we forget about the woman. Every symptom she has, we try to reassure her, we try to evaluate, we say it’s normal, it takes time to return to normal.”

Approximately half of the tests take three months to a year to return to their pre-pregnancy levels, highlighting the physiological impact of pregnancy, the Israeli authors write.

“This study provides a resource for understanding pregnancy and the postpartum period and demonstrates how it can be used to understand the mechanisms of systems physiology,” they say.

The study shows that it takes more than a “fourth trimester” for the woman’s body to recover. Instead, there is a “slow recovery” of 10 to 50 weeks for 31 of the 76 tests.

Markers associated with the liver and immune system, for example, took five months to recover, and markers associated with the liver took six months. A few other markers never recovered, even more than a year after pregnancy.

“Just because you give birth doesn’t mean everything goes back to normal,” said Dr. Morency. “We also don’t know if these changes are due to the pregnancy or to the fact that the woman changed behaviors during her pregnancy, for example, by quitting smoking.”

This is also evident from a clinical perspective, she added: women need much more than two or three weeks, or even six weeks, to “get their bodies back to normal” after childbirth.

The authors found that “the return of tests to baseline” during the postpartum period occurs “along a trajectory that differs from the trajectory of change during pregnancy.”

The Israeli researchers also observed that women who suffered from preeclampsia had elevated levels of blood cell fragments called platelets and a protein called ALT before pregnancy, compared to women who did not develop this problem. This could potentially help identify women at greatest risk of preeclampsia and provide them with the necessary follow-up.

“From a biochemical perspective, being able to target women who may not have had risk factors, if we are able to perform preconception interventions, would be ideal for preventing complications,” added Dr. Morency.

Postpartum adaptation is a distinct physiological process and not simply the inverse of pregnancy dynamics, the authors point out.

Some tests show a significant difference between their pre-pregnancy values ​​and their values ​​even at 80 weeks postpartum. These differences include, for example, a higher level of markers associated with inflammation. The differences could lead to postpartum behavioral changes and/or lasting physiological effects of pregnancy, the researchers say.

“We hope that this dataset will provide a deeper understanding of the biology of pregnancy and the postpartum period and inspire similar studies on other crucial physiological processes that occur over time,” the authors conclude.

The findings of this study were published in the journal Science Advances.

–This report by La Presse Canadienne was translated by CityNews