Birth Though Generations Study


PRIMARY INVESTIGATOR: K.M. HANLON-LUNDBERG MD, PHD


Humans have benefitted from help with childbirth for ages! 

The ways that we assist each other in conceiving, gestating, and birthing babies has become increasingly technologically enhanced - or technologically dependent?


INTERGENERATIONAL CESAREAN BIRTH IN THE US

Abstract accepted for presentation at the International Society for Evolutionary Medicine and Public Health (August 2024)

Cesarean birth (CB) is dramatically increasing compared to vaginal birth (VB) worldwide. This study evaluates the intergenerational relationship between birth modes.


Women anonymously provided birth histories of female relatives. Generations of participants were analyzed as family lineages of grandmothers (GM), mothers (M), index cases (I), and daughters (D). CB rates are presented as lifetime incidence per woman rather than per pregnancy. 85 index cases born between 1946-1980 (likely to have completed childbearing) were examined.


Study participants are of diverse ancestry and background. Lifetime risk of CB increased dramatically over the generations examined (GM 2.33%, M 8.24%, I 31.76%, D 51.22%).  Daughters of I who had any CB had a higher CB rate themselves compared to D of I who experienced all VB (66.67% vs 46.67%). Limited numbers in the D generation render significance using Mid-P Exact Test (0.11). No difference in parity was identified between all VB (2.45) and any CB (2.47) index groups.


Human birth is a biosocial practice. The optimal CB rate is debatable; evolutionary trade-offs of surgical birth are unknown. Emerging patterns of transgenerational CB have profound biosocial implications for our species. Larger populations over longer time may verify the trends identified in this pilot study. 

Background for this study: Technologic assistance with pregnancy and childbirth is common!

Despite widely held ideals of pregnancy and childbirth emphasizing natural processes, most US women experience many technological interventions during their pregnancies, from that first pee-on-a-stick test, to ultrasounds, blood tests, close monitoring of mom and baby during labor, and different options to help with labor pain.  Currently, about one of three US women are delivered by surgery - cesarean delivery (CD). The main question this study is trying to answer is whether persons who were themselves born by cesarean are more likely to give birth to their own children by cesarean as well. 


Worldwide, approximately one in five babies are born by CD. This represents two to three times the rate that the World Health Organization has identified as being associated with a decrease in maternal and neonatal mortality (World Health Organization 2015). This extraordinary transformation in human birth has occurred largely over the past 50 years - just 2 generations! Prior to 1900, CD was rare, and generally performed as a desperate procedure to save the life of the mother; by 1970 the CD rate in the US was about 5%. During that time, maternal and infant mortality declined dramatically, but maternal mortality leveled off around 1982, at which time the CD rate was around 20% (Taffel et al 1987).  In 2021, the CD rate in the US was 32.1 (Osterman 2022).

 

There are many reasons CD is done, including multiple gestations (twins, triplets, etc.), baby in a breech presentation, and also for maternal choice. The reasons why a person has a CD in the first place can put a woman at risk of complications, but further complications may be due to the CD itself (Burke and Allen 2020).  CD rates are known to be related non-medical social and cultural factors of both the pregnant person and their health care provider (Boerma et al 2018). Women identifying with disadvantaged communities may be more likely to have health challenges going into the pregnancy, may be less empowered to advocate for their own best interests, and may experience more complications related to baseline health and subsequent interventions (MacDorman et al 2021).

 

There are now many persons living in the US who were born by cesarean during the 6-fold rise in its use since 1970, including grandchildren of the first waves of persons experiencing CD. There is very little available information on the likelihood that a pregnant person who was born through CD will herself birth her children via CD. This study may be helpful:

·      To provide information to persons considering CD, whether elective or otherwise, of potential impact of CD for herself and possibly for her child’s reproductive future.

·      To help healthcare providers and healthcare system planners in developing obstetric services for future birthing persons.


Our individual choices set the stage for those of future generations!


References

Boerma, Ties, Carine Ronsmans, Dessalegn Y. Melesse, Aluisio JD Barros, Fernando C. Barros, Liang Juan, Ann-Beth Moller et al. "Global epidemiology of use of and disparities in caesarean sections." The Lancet 392, no. 10155 (2018): 1341-1348.

 

Burke, C. & Allen, R. (2020). Complications of Cesarean Birth. MCN, The American Journal of Maternal/Child Nursing, 45 (2), 92-99. doi: 10.1097/NMC.0000000000000598.

 

MacDorman, Marian F., Marie Thoma, Eugene Declcerq, and Elizabeth A. Howell. "Racial and ethnic disparities in maternal mortality in the united states using enhanced vital records, 2016‒2017." American journal of public health 111, no. 9 (2021): 1673-1681.


Osterman, Michelle JK. "Changes in primary and repeat cesarean delivery: United States 2016-2021." (2022)

 

Taffel SM, Placek PJ, Liss T. Trends in the United States cesarean section rate and reasons for the 1980-85 rise. Am J Public Health. 1987 Aug;77(8):955-9. doi: 10.2105/ajph.77.8.955. PMID: 3605474; PMCID: PMC1647267.