Thinking of having kids one day?
We got you.
We’re waiting longer than ever before to have kids—but biology hasn’t changed. We need more tools for planning families on our own terms. Now, thanks to the expertise of physicians and researchers, you can actually visualize your timeline. Explore the tool. Put structure to fertility. And you do you.
Let's get startedData sourced from The World Health Organization, Human Reproduction, The American Journal of Medical Genetics, The BMJ, and The Journal of Clinical Endocrinology & Metabolism.
Explore how hormones play a role in your timeline
% of women unable to have a child at each age
Your hormones are your fertility detectives—and now you can test them at home.
Shop Modern Fertility Hormone TestWant to dig into the data? Read Dr. Erin Burke’s post on building the Timeline Tool here.
Why a Timeline Tool? Get the scoop from CEO and Co-founder, Afton here.
1World Health Organization. Report of a WHO technical consultation on birth spacing: Geneva, Switzerland 13-15 June 2005. No. WHO/RHR/07.1. Geneva: World Health Organization, 2007.
A special thank you to Dr. Egbert R. te Velde for sharing data on age-related fertility with us and his helpful comments on the Tool.
Percentage of women unable to have a child at each age: Eijkemans, Marinus JC, et al. "Too old to have children? Lessons from natural fertility populations." Human Reproduction 29.6 (2014): 1304-1312.
Risk of Miscarriage: Andersen, Anne-Marie Nybo, et al. "Maternal age and fetal loss: population based register linkage study." Bmj 320.7251 (2000): 1708-1712.
Down Syndrome: Hecht, Christina August, and Ernest B. Hook. "Rates of Down syndrome at livebirth by one‐year maternal age intervals in studies with apparent close to complete ascertainment in populations of European origin: A proposed revised rate schedule for use in genetic and prenatal screening." American Journal of Medical Genetics 62.4 (1996): 376-385.
Menopause: Harlow, Siobán D., et al. "Executive summary of the Stages of Reproductive Aging Workshop+ 10: addressing the unfinished agenda of staging reproductive aging." The Journal of Clinical Endocrinology & Metabolism 97.4 (2012): 1159-1168.
AMH
Hansen, Karl R., et al. "Correlation of ovarian reserve tests with histologically determined primordial follicle number." Fertility and Sterility 95.1 (2011): 170-175.
Welt, Corrine K., and Enrico Carmina. "Lifecycle of polycystic ovary syndrome (PCOS): from in utero to menopause." The Journal of Clinical Endocrinology & Metabolism 98.12 (2013): 4629-4638.
Skiba, Marina A., et al. "Understanding variation in prevalence estimates of polycystic ovary syndrome: a systematic review and meta-analysis." Human Reproduction Update 24.6 (2018): 694-709.
Broer SL, van Disseldorp J, Broeze KA, Dolleman M, Opmeer BC, Bossuyt P, Eijkemans MJ, Mol BW, Broekmans FJ. Added value of ovarian reserve testing on patient characteristics in the prediction of ovarian response and ongoing pregnancy: an individual patient data approach. Human Reproduction Update. 2013;19(1):26–36.
Nelson, Scott M., et al. "Anti-Müllerian hormone-based approach to controlled ovarian stimulation for assisted conception." Human Reproduction 24.4 (2009): 867-875.
Bertone-Johnson, Elizabeth R., et al. "Anti-Müllerian hormone levels and incidence of early natural menopause in a prospective study." Human Reproduction 33.6 (2018): 1175-1182.
De Kat, Annelien C., et al. "Back to the basics of ovarian aging: a population-based study on longitudinal anti-Müllerian hormone decline." BMC Medicine 14.1 (2016): 151.
PRL
Gillam, Mary P., et al. "Advances in the treatment of prolactinomas." Endocrine reviews 27.5 (2006): 485-534.
Ellison, Peter T. "Energetics and reproductive effort." American Journal of Human Biology 15.3 (2003): 342-351.
Kauppila, Antti, et al. "Hypoprolactinemia and ovarian function." Fertility and Sterility 49.3 (1988): 437-441.
TSH
Krassas, G. E., Kris Poppe, and Daniel Glinoer. "Thyroid function and human reproductive health." Endocrine Reviews 31.5 (2010): 702-755.
Weeke, Jørgen, and Hans Jørgen G. Gundersen. "Circadian and 30 minutes variations in serum TSH and thyroid hormones in normal subjects." Acta Endocrinologica 89.3 (1978): 659-672.
Honbo, Ken S., Andre J. Van Herle, and Katherine A. Kellett. "Serum prolactin levels in untreated primary hypothyroldism." The American Journal of Medicine 64.5 (1978): 782-787.
LH
Hillier, S. G. "Current concepts of the roles of follicle stimulating hormone and luteinizing hormone in folliculogenesis." Human Reproduction 9.2 (1994): 188-191.
Perlman, Barry, et al. "The etiology of menopause: not just ovarian dysfunction but also a role for the central nervous system." Global Reproductive Health 3.2 (2018): e8.
FSH
Dewailly, Didier, et al. "Interactions between androgens, FSH, anti-Müllerian hormone and estradiol during folliculogenesis in the human normal and polycystic ovary." Human reproduction update 22.6 (2016): 709-724.
McLachlan RI, Wreford NG, O’Donnell L, de Kretser DM, Robertson DM 1996 The endocrine regulation of spermatogenesis: independent roles for testosterone and FSH. Journal of Endocrinology 148:1–9
Rose, Matthew P., Rose E. Gaines Das, and Adam H. Balen. "Definition and measurement of follicle stimulating hormone." Endocrine Reviews 21.1 (2000): 5-22.
Harlow, Siobán D., et al. "Executive summary of the Stages of Reproductive Aging Workshop+ 10: addressing the unfinished agenda of staging reproductive aging." The Journal of Clinical Endocrinology & Metabolism 97.4 (2012): 1159-1168.
van Rooij, Ilse AJ, et al. "Serum antimüllerian hormone levels best reflect the reproductive decline with age in normal women with proven fertility: a longitudinal study." Fertility and Sterility 83.4 (2005): 979-987.
E2
Lipson, Susan F., and Peter T. Ellison. "Endocrinology Comparison of salivary steroid profiles in naturally occurring conception and non-conception cycles." Human Reproduction 11.10 (1996): 2090-2096.
Perlman, Barry, et al. "The etiology of menopause: not just ovarian dysfunction but also a role for the central nervous system." Global Reproductive Health 3.2 (2018): e8.
fT4
Krassas, G. E., Kris Poppe, and Daniel Glinoer. "Thyroid function and human reproductive health." Endocrine Reviews 31.5 (2010): 702-755.
T
Shohat-Tal, Aya, et al. "Genetics of androgen metabolism in women with infertility and hypoandrogenism." Nature Reviews Endocrinology 11.7 (2015): 429.
Nardo, Luciano G., et al. "The relationships between AMH, androgens, insulin resistance and basal ovarian follicular status in non-obese subfertile women with and without polycystic ovary syndrome." Human Reproduction 24.11 (2009): 2917-2923.
Prizant, Hen, Norbert Gleicher, and Aritro Sen. "Androgen actions in the ovary: balance is key." Journal of Endocrinology 222.3 (2014): R141-R151.
Davison, S. L., et al. "Androgen levels in adult females: changes with age, menopause, and oophorectomy." The Journal of Clinical Endocrinology & Metabolism 90.7 (2005): 3847-3853.
Burger, Henry G. "Androgen production in women." Fertility and Sterility 77 (2002): 3-5.
The Modern Fertility Timeline Tool is provided for educational and informational purposes only and is not intended to replace any aspect of medical care. It is important to note that the tool only takes publicly available natural fertility data into account and that there are many other factors and unmeasurable characteristics that go into fertility and pregnancy. This tool provides evidence-based information (see links to sources) as a starting point for a conversation with your doctor. More information on data sources used in this tool here.