Here is an addendum to this post from the study author, Gayle Delong, PhD:
In connection with my paper, the question has been raised: Given that married women who had the HPV shot were less likely to conceive than those who did not receive the shot, were the former more likely to use birth control than the latter? My result that married women who received the shot were less likely to conceive could be explained if those women were more actively trying to prevent pregnancy than married women who did not receive the shot.
The three questions on NHANES that provide insights into contraception are 1) SXQ251: In the past 12 months, how often had you had sex without a condom? 2) RHD442: Are you taking birth control pills now? 3) RHQ520: Are you now using Depo-Provera or injectables to prevent pregnancy?
I seek to determine whether married women who received the HPV shot are more actively seeking to prevent pregnancy than married women who did not receive the shot. I define “actively seeking to prevent pregnancy” as women who at the time of the interview were using condoms at least half the time or taking the birth control pill or receiving an injectable. I find 51.5% of married women who did not receive the shot and 36.6% of married women who received the shot were actively seeking to prevent pregnancy. The 14.9% difference is statistically significant at the 1% level.
This finding suggests that a greater percentage of married women who received the shot should be conceiving compared with married women who did not receive the shot. However, my original study finds that married women who received the shot are less likely to conceive than married women who did not receive the shot. The finding of my original study is not the result of married women who received the HPV vaccine actively avoiding pregnancy more than women who did not receive the HPV shot. I’m happy to discuss details of my results with researchers who are interested.
A lowered probability of pregnancy in females in the USA aged 25–29 who received a human papilloma vaccine injection
Journal of Toxicology and Environmental Health, Part A, DOI: 10.1080/15287394.2018.1477640
ABSTRACT Birth rates in the United States have recently fallen. Birth rates per 1000 females aged 25–29 fell from 118 in 2007 to 105 in 2015. One factor may involve the vaccination against the human papillomavirus (HPV). Shortly after the vaccine was licensed, several reports of recipients experiencing primary ovarian failure emerged. This study analyzed information gathered in National Health and Nutrition Examination Survey, which represented 8 million 25-to-29-year-old women residing in the United States between 2007 and 2014. Approximately 60% of women who did not receive the HPV vaccine had been pregnant at least once, whereas only 35% of women who were exposed to the vaccine had conceived. For married women, 75% who did not receive the shot were found to conceive, while only 50% who received the vaccine had ever been pregnant. Using logistic regression to analyze the data, the probability of having been pregnant was estimated for females who received an HPV vaccine compared with females who did not receive the shot. Results suggest that females who received the HPV shot were less likely to have ever been pregnant than women in the same age group who did not receive the shot. If 100% of females in this study had received the HPV vaccine, data suggest the number of women having ever conceived would have fallen by 2 million. Further study into the influence of HPV vaccine on fertility is thus warranted.
Gayle DeLong, PhD, is an Associate Professor of Economics and Finance in the Bert W. Wasserman Department of Economics and Finance at Baruch’s Zicklin School of Business. Dr. DeLong has published in leading journals, including Journal of Finance, Journal of Financial Economics, Journal of International Money and Finance, Financial Management, and Journal of Financial Research. Research interests include bank acquisitions, regulatory capture, and conflicts of interest. DeLong, the 2013 recipient of the Abraham J. Briloff Prize in Ethics as well as the 2010 recipient of the Zicklin School of Business Teaching Excellence Award, holds a PhD in finance and international business from New York University.
Citation: Gayle DeLong (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, DOI: 10.1080/15287394.2018.1477640