According to the latest birth report from the Center for Disease Control (CDC), birth rates for women under 30 are declining and the rate of teen pregnancy has dropped by half. In a previous post, we covered an article that found a strong correlation between education and marriage and the increasing age of first-time mothers. Superficially it appears many women are simply waiting, but there is a study published this year that suggests there is another culprit in the mix that has heretofore been overlooked.
A recent study comparing pregnancy rates and the HPV (human papillomavirus) vaccination found a decreased rate of pregnancy among women age 25-29 who had received an HPV vaccine compared with those who had not. The first HPV vaccine was licensed in 2006 and the recent decline in birth rate begins in 2007 and has continued to decrease since then; this study suggests the two events may be related.
The study looked at data collected from the National Health and Nutrition Examination Survey (NHANES) conducted by the CDC. Between 1999-2014 this survey asked women (age 12+) if they had ever been pregnant (which also included current pregnancy, live births, miscarriages, stillbirths, ectopic pregnancies, and abortions). Between 2007-2014, the survey also asked if the participant (age 9+) had ever received an HPV vaccine (noted in the study, NHANES stopped asking surveyed individuals both of these questions in 2014). Therefore, the data compared in the study included 700 women aged 25-29 surveyed between 2007 and 2014. The small age range was intended to minimize the affect of comparing older women who are more likely wanting kids with younger women who are more likely trying not to get pregnant.
Overall the data presented shows vaccinated women had a pregnancy rate of 35.3%, while unvaccinated women had a pregnancy rate of 61.1%. When split into ‘ever-married’ and ‘never married’ cohorts, unsurprisingly the group of women who were not married had a lower rate of pregnancy – sexually active women in this group are likely actively trying to avoid pregnancy. Any contraceptive method would mask any evidentiary lack-of-pregnancy correlated with vaccination. However, looking solely at the group of women who were married (therefore more likely to be seeking conception), those who had been vaccinated had a much lower rate of pregnancy (50.1%) than their unvaccinated counterparts (76.9%).
Also the study notes there were a greater percentage of vaccine recipients who were college-educated. Though the author didn’t make any further comment on the cause, perhaps this is because there is a greater vaccination outreach on campus and easy access to student clinics.
Animal studies have suggested aluminum can disrupt normal function of hormones1,3. Unfortunately there has not yet been a study devoted solely to investigating affects of aluminum and fertility. The study mentions the presence of aluminum in the HPV vaccines and notes perhaps the vaccination is affecting birth rate through premature ovarian failure (POF) as a consequence of the aluminum. However, it does not provide any evidence of this; the author simply puts the information out there, but adds there may be other contributing factors yet identified.
There are a few disclaimers of note: We do have to point out that this study is strictly a comparison of data points looking at association of two events, not necessarily causal link. The study is suggesting HPV vaccination and decreased pregnancy rate may be associated, but it does not claim that HPV vaccination is the cause of the decreased pregnancy rate. Also the study does not indicate that if you yourself were vaccinated that you may have fertility issues, and it doesn’t provide any information regarding how the vaccine might affect fertility, if it does. The long list of disclaimers sent up a red flag for me. It’s as if the study threw out a bunch of information and then said they might be related, but then again they might not. Also, the author is not an epidemiologist- she has a Ph.D. in International Business & Finance and her CV is filled with publications regarding bank mergers and risk allocation. Numbers and data are her forte, but disease models and epidemiology are not. Also, there are a few points that make me think the author may not be as objective as a scientist should be. Therefore, I think the data is interesting, but shouldn’t be read into too deeply without more data to back it up.
Likely this study is going to be circulated around the Internet because it has such a profound implication. However, it doesn’t seem that its findings are quite as profound as they claim. When I first read the abstract, it really piqued my interest, but the more I dug into it, the more skeptical I became. It seems like it is a study that is making conclusions while looking at just the tip of the iceberg. There is just so much going on below the surface that isn’t being explored which leaves me questioning the validity of the claim. So even though I am giving you the information presented in the paper, take it with a grain or two of salt.
¹Correia, T., Narcizo, A., Bianchini, A., & Moreira, R. (2010). Aluminum as an endocrine disruptor in female Nile tilapia (Oreochromis niloticus). Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology,151(4), 461-466. doi:10.1016/j.cbpc.2010.02.002
2Delong, G. (2018). A lowered probability of pregnancy in females in the USA aged 25–29 who received a human papillomavirus vaccine injection. Journal of Toxicology and Environmental Health, Part A,81(14), 661-674. doi:10.1080/15287394.2018.1477640
3Sun, H., Hu, C., Jia, L., Zhu, Y., Zhao, H., Shao, B., . . . Li, Y. (2011). Effects of Aluminum Exposure on Serum Sex Hormones and Androgen Receptor Expression in Male Rats. Biological Trace Element Research,144(1-3), 1050-1058. doi:10.1007/s12011-011-9098-6