
Details taken from Growth of the birth canal in adolescent girls, by M L Moerman [1]
Note: Menarche is defined as the first menstrual period in a female adolescent.

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[1] https://pubmed.ncbi.nlm.nih.gov/7091223/
Growth of the birth canal in adolescent girls
M L Moerman
PMID: 7091223 DOI: 10.1016/0002-9378(82)90542-7
Abstract
The growth and development of four dimensions of the pelvic birth canal are analyzed from a longitudinal sample of 9 well-nourished girls aged 8 through 18. Compared with stature, the pelvic basin grows more slowly and continuously through late adolescence. Similarly, size of the birth canal is smaller the first 3 years past menarche than at age 18. At low gynecologic ages, a significantly greater percentage of growth to adult size is required in the pelvis as compared to stature, and growth of the birth canal continues beyond the asymptote for statural increase. The pelvis is smaller and less mature among girls with early menarche than among girls with late menarche at the same menarcheal ages. These results indicate that immaturity of the birth canal of the pelvis may have significance for obstetric risks among young teenage primiparous girls.
[2]Can a baby get stuck in the birth canal?
https://rayneslaw.com/can-a-baby-get-stuck-in-the-birth-canal/
Last accessed June 2025
[3]Maternal age and risk of labor and delivery complications
Patricia A Cavazos-Rehg, Melissa J Krauss, Edward L Spitznagel, Kerry Bommarito, Tessa Madden, Margaret A Olsen, Harini Subramaniam, Jeffrey F Peipert, Laura Jean Bierut
Table 5
Odds of complication during labor and delivery for age groups, adjusted for demographics, type of birth, and comorbidities
https://pmc.ncbi.nlm.nih.gov/articles/PMC4418963/
Last accessed June 2025
[4] Comorbidity: the simultaneous presence of two or more diseases or medical conditions in a patient.
[5]Mortality and Acute Complications in Preterm Infants
Institute of Medicine (US) Committee on Understanding Premature Birth and Assuring Healthy Outcomes; Behrman RE, Butler AS, editors.
Washington (DC): National Academies Press (US); 2007.
https://www.ncbi.nlm.nih.gov/books/NBK11385/
Teen Pregnancy and Risk of Premature Mortality
https://pmc.ncbi.nlm.nih.gov/articles/PMC10940968/
Last accessed June 2025
Ray JG, Fu L, Austin PC, Park AL, Brown HK, Grandi SM, Vandermorris A, Boblitz A, Cohen E. Teen Pregnancy and Risk of Premature Mortality. JAMA Netw Open. 2024 Mar 4;7(3):e241833. doi: 10.1001/jamanetworkopen.2024.1833. PMID: 38483391; PMCID: PMC10940968.
https://www.advocatesforyouth.org/wp-content/uploads/storage/advfy/documents/fsmaternal.pdf
The influence of maternal age and parity on child‐bearing with special reference to primigravidae aged 15 years and under
In singleton births, maternal and fetal survival were poorest among primigravidae aged ≤15 years and also in the highly parous women aged ≥30 years. The young teenage girls constituted 6% of the survey population and 30% of the 174 maternal deaths, while the highly parous older women made up 10% of the survey population and 20% of the maternal deaths. The perinatal death rates per 1000 singleton deliveries were 180 for the young teenage girls, 150 for the highly parous groups had under 100 for the others. The major obstetric problems were dystocia due chiefly to contracted pelvis, anaemia, eclampsia, haemorrhage and infections. Emphasis is laid on the fact that the problems of these high-risk groups have their roots in the prevailing social attitudes which universal formal education stands the best chance of changing.
https://pmc.ncbi.nlm.nih.gov/articles/PMC411126/
The youngest mothers—those aged 14 and under—faced the greatest risks. Research from Bangladesh showed that the risk of maternal mortality may be five times higher for mothers aged 10 to 14 than for mothers aged 20 to 24.