Book Review: The Fertility Formula (Dr. Natalie Crawford)

As a therapist who works in the field of reproductive and infertility counselling, I see every day the dangers of pseudoscience and misinformation. Desperate infertility patients hoping to find an explanation for their unexplained infertility go searching on the Internet for answers their doctors are unable to give them. Unfortunately, this opens to door to predatory behaviour from a variety of sources hoping to capitalize on this desperation. There are chiropractors, naturopaths, acupuncturists, as well as IVF mindset coaches and more offering infertility patients not only answers but also expensive solutions, most of which have little evidence of any efficacy.

The easiest way to panic someone dealing with infertility is to tell them stress is the cause. Bonus points if you throw in the terms ‘chronic inflammation’ and ‘cortisol’. Concern over this often leads my clients to go to extreme lengths to minimize stress including taking a less demanding job they do not actually enjoy, or taking months to years of medical leave, or quitting their job altogether, despite the financial ramifications. It does not help that this belief is deeply ingrained in society, that if a woman cannot conceive and an obvious medical cause cannot be identified, it must be her anxiety/stress (i.e. hysteria) which is the cause. By the way, nobody ever says to the man in a couple with unexplained infertility that his stress could be the cause. My clients interpret chronic stress as being basically ‘life’: jobs, people, traffic jams, etc., or just feeling anxiety about their infertility.  If just the normal stresses and strains of everyday life caused infertility, humans would have gone extinct centuries ago. And if anxiety about infertility was the cause of infertility, then most cases of infertility would be untreatable. As I tell my clients, I rarely come across people not somewhat anxious and upset about the fact that they are dealing with infertility and often it gets worse rather than better when they start treatment. So IVF and other treatments would never work if the cause was just ‘stressing about their infertility’.

Unfortunately, one thing I have learned is that a person’s credentials do not necessarily guarantee the accuracy of the information they espouse. Such is the case with well known and respected MD, Natalie Crawford, who is a DOUBLE BOARD CERTIFIED fertility doctor in Austin, Texas. To me, she is one of the most dangerous types of science communicators because 80% of what she says is true while the other percent is unsubstantiated, potentially harmful claims. It is around the issue of stress and infertility where her claims get murky. The last time I asked her to substantiate some of her claims she told me to read her new book, the Fertility Formula, so I did. The news is not good.

If you want straightforward information about reproductive systems, fertility, hormones, and types of fertility treatments, the book delivers, but when it delves into causes of infertility and issues related to stress and chronic inflammation, things go off the rails.

Stress is first of all not well defined but is identified by Crawford as a factor that contributes to chronic inflammation and leaky gut, both which she claims will decrease reproductive success. When I tracked down her references and read the studies, it was obvious that either Crawford misunderstands the findings of the research or intentionally manipulates how she reports them to fit her narrative. For example, one study she sites as evidence that chronic stress has a negative impact on women’s fertility (Pal et al., 2010), defines chronic stress as history of abuse or drug use, in fact their conclusion is:

Our findings identify aspects reflecting 'chronic' lifetime psycho-social stressors (i.e., personal history of abuse and of recreational drug use and/or family history of drug use) rather than 'current' stress (as reflected by dysphoric mood score and morning serum cortisol level) as detriments to ovarian reserve (i.e., were predictive of higher FSH levels and of an enhanced likelihood for DOR).

There is a systematic review article (Zanettetoullis et al., 2024) which does find some connection between self-reported stress and biomarkers and results of IVF. The outcome variable I focus on most is live birth rates because as I always remind my clients, the ultimate goal is not embryos or clinical pregnancy (which includes chemical pregnancies and miscarriages), the goal is to actually have a child!

Here is what they conclude:

The live birth rate was found to be associated with both chronic and acute stress; however, it was unclear whether stress during or before the IVF process is related to the live birth rate, because other factors are also involved during pregnancy. Specifically, the operationalization of a diverse array of psychometric instruments by a number of studies made it difficult to ascertain whether they were measuring chronic or acute stress. This led the researchers of this review to further research the available literature, but this practice did not produce studies that fit the search criteria, especially concerning the different time points of IVF. Some of the research in this systematic review suggested that follicular cortisol may have an impact in egg retrieval, fertilization, and pregnancy time points. Studies indicated that higher follicular fluid cortisol concentrations were indeed related to higher rates of fertilisation, egg retrieval rate, and pregnancy. This review also revealed no correlation regarding salivary and follicular cortisol concentrations. It is proposed that this research area should be expanded, because even though higher follicular fluid is a promising marker, the studies reviewed were not explicit nor based on follicular cortisol. Follicular fluid can be a predictor of success of the IVF treatment, therefore creating a prognostic biomarker. This is an issue that needs to be further analyzed in prospective studies as a predictive biomarker of stress in IVF success in every timepoint separately.

But here is the thing, tell infertility patients that they need to reduce their stress or it will negatively affect their chances of conceiving and guess what happens? They get more stressed. Shocker. When I meet with my clients, I remind them that life is stress. Everyone has some stress in their life unless they are in a friggin’ coma. And anyone dealing with infertility is experiencing distress about the infertility. The best thing to do is accept that, stop over-fixating on trying to optimize/control every aspect of their body and mind, get off the damn internet, and try to spend time doing things they enjoy that can potentially distract them from the infertility even if just for a short period of time. The response I get from them is always something like, “Thank you for saying that, I feel so much better.”

This also leads into another rant. I am sick and tired of any stress being seen as something to avoid, and people seeing themselves as so fragile. Lots of research (Check out the work of Alia Crum and Kelly McGonigal) and the benefits of stress (exercise is a form of stress!) and the impact of our perceptions of stress. If you see any form of stress or experience of anxiety as bad and toxic, it is more likely to lead to negative health outcomes. But just like we need to stress our bodies with exercise to make our heart, bones, and muscles stronger, some degree of emotional stress and discomfort is necessary to become more emotionally resilient. You can also explore the research on post-traumatic growth if you want to delve into that more.

What really pisses me off is Dr. Crawford’s list of signs of ‘chronic inflammation’, which is, of course, the result of any sort of chronic stress:

First off, inflammation is a normal and necessary response in the body. Yes, chronic inflammation is not good. But based on this list, every living human has it and is in trouble. Are you fucking kidding me?

Another big red flag in the book is her inclusion of leaky gut syndrome, which is not even widely recognized as a condition. Once again, her narrative is that chronic stress leads to leaky gut which leads to chronic inflammation which will negatively affect fertility. No studies have been done on this, by the way. Furthermore, when I explored the research on leaky gut by those in the gastroenterology field who do believe it exists, the consensus seems to be it is not caused by stress or diet, does not extraintestinal symptoms, nor is it diagnosable by endoscopy, blood work or symptoms alone. Nevertheless, according to Dr. Crawford, these are symptoms of leaky gut:

Well apparently, virtual all of us also have leaky gut.

The other 2 red flags in the book are Dr. Crawford’s mention of cycle syncing your workouts. The evidence (based on the research by experts in that field!). Suggests there is no benefit for your health or training to workout a specific way. Basically, just exercise over the course of your menstrual cycle in the way that feels best to you. The end.

So, do I recommend this book? Certainly not unless you are simply interested in understanding the basics of infertility and reproduction. If you are an already anxious infertility patient, sure, it is going to give you a very specific blue print for ‘supposedly’ though without very much actual evidence, improving your fertility. But it may also make your infertility journey more stressful and, I will add, probably lead you to self-blame if your and not successful. I see this all the time, “I had one glass of wine/an ice cream cone/a stressful project at work/…and that must be why things failed.”

I tell my clients that the best way to get through infertility is make peace with the lack of control involved. In terms of what they can do lifestyle-wise? For women, take whatever medications and supplements recommended by your fertility doctor, avoid smoking/marijuana use, drinking, try to eat a balanced, mostly unprocessed diet, try to get good sleep, and exercise (what you do depends on your prior activity/level of fitness). For men, there is definitely more evidence that certain supplements can help with sperm quality, and also avoid cigarettes/marijuana/alcohol, heat near the testes, and eat a balanced, mostly unprocessed diet, exercise and get good sleep. Also important for both men and women is to treat any underlying chronic illnesses (type II diabetes, high blood pressure, thyroid condition, etc.), and try to be in a healthy weight range because being overweight or underweight can negatively impact fertility. Well hey, if you didn’t notice, most of this is generally what we recommend to anyone and everyone to maximize your health! But you can do absolutely everything right and go to all the extreme lengths Dr. Crawford discusses and there are NO GUARANTEES. A lot of aspects of fertility outcomes, like most things in life, are outside of our control.

Do I think this book will be successful. Absolutely. As I said, humans hate not getting answers and not having control and her claims that you do have more control than what you might have been told is going to appeal to a lot of desperate people. Unfortunately, I just think this is fear mongering.