What actually has evidence — and what does not

higher odds of infertility in smokers than non-smokers

Pooled data show smokers have substantially higher odds of infertility, a longer time to pregnancy, earlier menopause, and lower success in IVF. In men, smoking lowers count, motility and morphology and raises sperm DNA fragmentation.

Source: Augood, Duckitt & Templeton — Human Reproduction, 1998; ASRM/ESHRE guidance

What it does not say: Damage from smoking is partly reversible: fecundability improves after quitting, and sperm parameters after roughly 3 months — one full sperm cycle.

prevents most neural tube defects when started before conception

Periconceptional folic acid substantially reduces neural tube defects. It has to be on board before the pregnancy test is positive, because the neural tube closes in the first month.

Source: De-Regil et al. — Cochrane Database, 2015; MRC Vitamin Study, 1991

What it does not say: This is about a healthy pregnancy, not about conceiving faster. Dose depends on your history — higher if there has been a previous affected pregnancy, diabetes or certain medicines.

in the fertile window gives the highest per-cycle pregnancy rates

Pregnancy rates are highest with intercourse every one to two days during the fertile window, and remain high at every two to three days across the cycle — higher than with calendar-targeting a single predicted day. The fertile window is about six days, ending on the day of ovulation.

Source: Wilcox, Weinberg & Baird — New England Journal of Medicine, 1995; ASRM committee opinion

What it does not say: App predictions are calendar arithmetic, not biology. Ovulation strips or cervical mucus are better, and neither is needed if frequency is already every 2 to 3 days.

of women go on to have a healthy pregnancy after a loss

Most women who miscarry go on to have a successful pregnancy — including most of those who have had two losses. A loss is not a verdict on what comes next.

Source: RCOG — recurrent and sporadic miscarriage guidance

What it does not say: After two or more losses there is a defined work-up. "Bad luck" is a reasonable conclusion after that work-up, not instead of it.

lower risk of ovulatory infertility in the highest-adherence group

Women whose diet scored highest on a fertility-diet pattern (more vegetable protein and whole grains, less trans fat and refined carbohydrate, high-fat dairy instead of low-fat, plant iron, a multivitamin) had a markedly lower risk of infertility due to ovulation problems than women scoring lowest.

Source: Chavarro, Rich-Edwards, Rosner & Willett — Obstetrics & Gynecology, 2007

What it does not say: Observational: diet was not randomly assigned, so part of the effect may come from everything else that travels with a healthier diet. It applied to ovulatory infertility, not to tubal or male factor.

live birth in the highest vs lowest adherence group, women under 35

Among women under 35 having their first IVF cycle, those in the top third for Mediterranean-diet adherence in the six months before treatment had a higher live-birth rate than those in the bottom third.

Source: Karayiannis et al. — Human Reproduction, 2018

What it does not say: A single centre, a modest number of women, and observational. It did not hold in women over 35 in this study.

weight loss restored ovulation in most women in these programmes

In lifestyle programmes for overweight women with anovulatory infertility, a modest weight loss restored spontaneous ovulation in the majority and was followed by high pregnancy rates — without reaching an "ideal" weight.

Source: Clark et al. — Human Reproduction, 1995 & 1998; and subsequent lifestyle RCTs

What it does not say: Early studies were small and uncontrolled. Larger randomised trials since have shown lifestyle programmes improve ovulation and natural conception more reliably than they improve IVF live-birth rates.

odds of menstrual disruption in shift workers

Women doing shift work have higher odds of menstrual cycle disruption and of subfertility; night work is also associated with lower antral follicle counts in some studies. Melatonin, made only in darkness, acts as an antioxidant inside the follicle.

Source: Stocker, Macklon, Cheong & Bewley — Obstetrics & Gynecology, 2014

What it does not say: Observational, and shift work travels with other exposures. No trial has shown that fixing sleep alone raises pregnancy rates — but sleep is free, and it changes appetite, mood and hormone rhythm within weeks.

higher miscarriage rate with high DNA fragmentation

Pooled analyses link high sperm DNA fragmentation with higher miscarriage rates after IVF and ICSI, and with poorer embryo development — even when count, motility and morphology look normal.

Source: Robinson et al. — Human Reproduction, 2012; Zini et al. — Human Reproduction, 2008

What it does not say: Testing is not recommended for everyone, and cut-offs differ between laboratories. It is most informative after unexplained infertility, recurrent loss or repeated IVF failure.

associated with reduced fecundability in cohort studies

Heavier drinking is associated with taking longer to conceive and with poorer IVF outcomes. Findings at light drinking levels are inconsistent, and no safe level is established once pregnant.

Source: Mikkelsen et al. — BMJ, 2016; Rossi et al. — Obstetrics & Gynecology, 2011

What it does not say: The evidence at one or two drinks a week is genuinely unclear. Once pregnant, the advice is none.

music reliably reduces anxiety during medical procedures

Across many randomised trials, listening to music before and during procedures lowers anxiety and, in several studies, pain scores. Trials during oocyte retrieval, embryo transfer and hysteroscopy report the same effect on distress.

Source: Bradt, Dileo & Shim — Cochrane Database, 2013; procedural RCTs in assisted reproduction

What it does not say: The anxiety benefit is solid and worth having on its own. Pregnancy-rate effects are not established — the few fertility trials are small and were not designed to answer that question.

group support and skills-based programmes reliably lower anxiety and depression

Across randomised and controlled studies, psychosocial interventions for people in fertility treatment reduce anxiety and depressive symptoms. Group formats that teach skills and share experience do better than one-to-one counselling alone, and the effect is largest in those who were most distressed to begin with.

Source: Boivin — BMJ, 2003; Frederiksen et al. — BMJ Open, 2015

What it does not say: Some meta-analyses also report higher pregnancy rates alongside lower distress, but those trials are heterogeneous and were not designed to test it — less distress is the honest reason to join a circle, not a better chance of a baby.

low AMH did not lower the chance of conceiving within 6 or 12 cycles

In 981 women aged 30–44 trying to conceive without a history of infertility, those with a low AMH (under 0.7 ng/mL) were no less likely to conceive over 6 and 12 cycles than women with normal AMH. The same was true for a raised FSH. AMH counts what is left in the ovary; it is a poor guide to this month.

Source: Steiner, Pritchard, Stanczyk et al. — JAMA, 2017

What it does not say: This was in women without a known fertility problem, and it says nothing about IVF: AMH does predict how many eggs a stimulation will yield, which is why your clinic still measures it. It does not predict the quality of those eggs.

pregnancy within 36 weeks after ablation versus diagnostic laparoscopy alone

In the largest randomised trial, removing visible minimal-to-mild endometriosis at laparoscopy raised the pregnancy rate over the following months compared with looking and doing nothing. Pooled with the other trial in this question, the benefit is real but modest — roughly one extra pregnancy for every eight to twelve women operated on.

Source: Marcoux et al. — New England Journal of Medicine, 1997; Duffy et al. — Cochrane Database, 2014

What it does not say: A second trial found no difference, the pooled effect rests on few events, and this is about minimal-to-mild disease and natural conception. Surgery for endometriomas before IVF is a different decision with its own risk to ovarian reserve — that one belongs to your surgeon, not to a circle.

moderate activity shortened time to pregnancy; vigorous training lengthened it in lean women

In a large prospective cohort of women planning pregnancy, moderate physical activity was associated with a modestly shorter time to pregnancy across all body types. Vigorous activity was associated with reduced fecundability in normal-weight women — but not in overweight women, where it helped. The useful dose is closer to a daily walk than to daily training.

Source: Wise, Rothman, Mikkelsen et al. — Fertility and Sterility, 2012

What it does not say: Observational, and activity was self-reported in the original study — which is exactly the measurement problem a connected phone fixes. It does not mean a lean woman should stop exercising; it means very high training loads are worth discussing.

average gap between self-reported sleep and sleep measured at the wrist

When the same nights were both asked about and measured with a wrist actigraph, people reported sleeping around 0.8 hours more than they actually did, and the gap was widest in those sleeping least. This is not dishonesty — time in bed feels like time asleep. It is the single best reason to let a phone answer the sleep question instead of a memory.

Source: Lauderdale, Knutson, Yan et al. — Epidemiology, 2008

What it does not say: Consumer watches are not actigraphs or sleep studies either: they estimate sleep from movement and heart rate, and they tend to overestimate sleep in people who lie still while awake. A measured number is better than a remembered one, not perfect.

odds of pregnancy in meta-analysis of psychological interventions

Structured mind–body programmes (relaxation, breathing, cognitive work, group support) reliably reduce anxiety and depression during treatment, and pooled analyses have found higher pregnancy rates in women who took part.

Source: Frederiksen et al. — BMJ Open, 2015; Domar et al. — Fertility & Sterility, 2000 & 2011

What it does not say: The distress benefit is solid; the pregnancy-rate benefit is not. Trials were small, methods varied, and some well-run studies found no effect on pregnancy. Stress does not cause infertility — and nobody should be told their treatment failed because they did not relax enough.

cooler than core body temperature is what sperm production needs

Sustained scrotal heating — long seated hours, laptops on the lap, saunas and hot baths — measurably lowers sperm concentration and motility in experimental studies, and the effect reverses within a few months of removing the heat.

Source: Jung & Schuppe — Andrologia, 2007; occupational heat-exposure cohorts

What it does not say: Studies are small and the size of the effect varies a lot between men. The advice costs nothing and is reversible, which is why it is worth doing anyway.

live-birth evidence is low quality and unresolved

The Cochrane review found that antioxidants may increase live birth and clinical pregnancy in subfertile men, but rated the evidence as low quality — the trials were small, inconsistent, and used many different combinations.

Source: Smits, Mackenzie-Proctor, Yazdani et al. — Cochrane Database, 2019

What it does not say: Not a reason to avoid them, and not a reason to buy the most expensive blend. Very high doses can be counterproductive. Ask your doctor what is worth taking in your case.

ovulation and insulin markers improve; live-birth evidence still weak

Trials in women with PCOS show myo-inositol improves insulin sensitivity, restores ovulation in a substantial proportion, and improves cycle regularity — with very few side effects.

Source: Showell et al. — Cochrane Database, 2018; multiple PCOS RCTs

What it does not say: The Cochrane review found no clear evidence yet for live birth. Dose and duration should come from your doctor, not from a shelf.

sufficient vitamin D linked to higher live birth; supplementing is unproven

Women with sufficient vitamin D have higher live-birth rates after IVF than women who are deficient in pooled observational data. Deficiency is close to universal among indoor workers in India.

Source: Chu et al. — Human Reproduction, 2018

What it does not say: Association, not proof: trials of supplementing to improve IVF outcomes have not shown a clear benefit. Correcting a real deficiency is still worth doing for your bones and general health — test first, do not guess the dose.

reliable benefit for anxiety and wellbeing; no reliable pregnancy-rate evidence

Yoga during fertility treatment consistently reduces anxiety, depression and treatment-related distress in small trials and reviews. What it has not done is demonstrate a reliable increase in pregnancy or live-birth rates in good-quality studies.

Source: Oron et al. — Reproductive BioMedicine Online, 2015; Darbandi et al., 2018

What it does not say: We include yoga because feeling steadier, sleeping better and staying in treatment are worth having on their own — not because it has been shown to make you pregnant. Anyone promising a percentage here is guessing.

of fertile windows detected by an overnight wrist sensor, in the study population

Continuous overnight skin temperature, pulse rate and breathing rate change measurably across the cycle. A wrist sensor worn nightly identified the fertile window in around nine out of ten cycles — and unlike a basal thermometer, which confirms ovulation after it has happened, these signals begin shifting before it.

Source: Goodale, Shilaih, Falco et al. — Journal of Medical Internet Research, 2019

What it does not say: Manufacturer-run, in regular cycles, and detection is not conception: no trial has shown that wearing the device raises the pregnancy rate. It performs worst in exactly the cycles that need it most — irregular ones, PCOS, and shift work.

no study shows drinking more water raises pregnancy rates

Hydration matters for cervical mucus quality, blood volume, semen volume, constipation and headaches — and every glass of water is a glass that is not a sugary drink. But no trial has tested water intake against pregnancy rates, and we will not pretend otherwise.

Source: Physiology and general-health guidance; no fertility outcome trials

What it does not say: What does have evidence is what you drink instead: sugar-sweetened drinks are associated with lower fecundability (Hatch et al., Epidemiology, 2018), and heating food or drink in plastic is a recognised route of exposure to endocrine-disrupting chemicals.

kitchen foods are safe and nourishing; concentrated herbal products are not proven and can interact

The recipes here are ordinary foods — soaked nuts, amla, methi water, ragi, moringa, turmeric milk — chosen because they are nutrient-dense and part of everyday Indian cooking. They are not medicines and they have not been shown to raise pregnancy rates.

Source: Reviews of complementary medicine in fertility care; ASRM/ESHRE guidance

What it does not say: Concentrated herbal extracts are a different matter: they can interact with thyroid medicine, blood thinners, sedatives and fertility drugs, and several are unsafe in pregnancy. Tell your doctor everything you take, and stop herbal products during stimulation and after a transfer unless your doctor has said otherwise.

no tuning or beat frequency has been shown to change a fertility outcome

Binaural beats have small, mixed trials suggesting a modest effect on anxiety; 432 Hz tuning has no credible evidence of any specific physiological effect over any other tuning. We offer both because people enjoy them, and we label them honestly.

Source: Garcia-Argibay et al. — Psychological Research, 2019 (binaural beats meta-analysis)

What it does not say: If a sound helps you sleep or settles you before a scan, that is a real benefit. It is not a treatment, and anyone selling a frequency as a fertility cure is selling you something.

no wearable or app score has been shown to increase live births

Wearables measure movement, heart rate, variability and how long you lay still. Those are real measurements and they make a lifestyle picture far more honest than a questionnaire. None of them has been shown in a trial to raise the chance of a pregnancy, and no app — including this one — can convert a step count into a fertility outcome.

Source: Absence of evidence, stated deliberately

What it does not say: This is the honest limit of the feature. Connecting your phone makes your score describe you more accurately, and can surface a sleep or activity problem worth fixing. It is a better mirror, not a treatment — and a device that makes you anxious about your numbers is costing you more than it gives.