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The surprising science of “trimester zero” and what parents can do before trying for a baby

The surprising science of “trimester zero” and what parents can do before trying for a baby

Thinking about trying for a baby? Experts say the months before conception – aka trimester zero – can shape fertility and pregnancy health. From folic acid and sleep to sperm health, here’s what doctors and real mums say actually helps.

An alarm clock and the last time for pregnancy

Serafina Kenny

Published: March 12, 2026 at 8:57 AM

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You’ve heard of trimesters one, two, and three — but what about trimester zero? In an age of wellness and health optimisation, women are starting to think about the period before conception as just as integral to their pregnancies as the actual gestational period.

But do we need to be training our bodies for pregnancy? If so, what can we do in trimester zero to actually help boost fertility, egg quality and pregnancy outcomes? And should dads be thinking about pre-conception health, too?

We spoke to Dr. Tim Bracewell-Milnes, consultant gynaecologist at HCA Healthcare UK’s Lister Fertility Clinic, about what to do in trimester zero, as well as asking real mums what they did to prepare for pregnancy — and whether it helped.

Why does health before conception matter?

Trimester zero isn’t an official medical term, but Tim says that “it is a concept backed by science as it aims to highlight that preconception health (the health of the parents before they are pregnant) could have an influence on the long-term health of the baby.”

Parental health also impacts fertility and pregnancy outcomes, meaning that being healthier can make it easier to conceive and reduce risks of things like gestational diabetes in pregnancy and babies with low birth weights.

This is true for both mums and dads.

The health of the dad-to-be matters just as much as that of the mum-to-be so both parents making healthy lifestyle changes is beneficial.

Dr Tim Bracewell-Milnes, consultant gynaecologist at HCA Healthcare UK’s Lister Fertility Clinic

“For mothers, factors such as nutrition, weight, folate levels, chronic conditions (such as diabetes or thyroid issues), alcohol use, smoking and medications can affect egg quality, implantation, and early foetal development.”

Meanwhile, “for fathers, sperm health is heavily influenced by lifestyle, age, weight, smoking, alcohol, and environmental exposures,” he says, adding that “sperm quality is important because it affects the chance of conception, as well as embryo development in the earliest days of pregnancy.”

Making lifestyle changes in trimester zero can help with conception and pregnancy

Woman mixing delicious superfood salad ingredients with wooden spoons in kitchen

“Small, sensible steps to improve general health and wellbeing can increase the chances of conceiving safely, but many children are born healthy even when real life isn't perfect,” Tim says.

It’s important to note that not all hopeful parents-to-be can improve their fertility with lifestyle changes — some people have fertility issues that require more intervention or that can’t be addressed without medical support. And you also don’t have to be in perfect health to get pregnant or have a healthy child.

Conception takes time, and is, in some sense, a numbers game. A young, healthy couple have around a 25-30% chance of conceiving in the first few months. This rises to 80% within one year. The good news is that at least half of those that don’t will conceive in the following year.

Dr Tim Bracewell-Milnes, consultant gynaecologist at HCA Healthcare UK’s Lister Fertility Clinic

However, making healthy lifestyle changes can increase your chances of conceiving and having a healthy pregnancy for most cases.

“Think of it this way: you’re creating the healthiest environment for your baby to grow in, which of course impacts how they develop. While you don’t have to be perfect, or extreme, taking moderate steps can be very beneficial and help you feel better and more confident about the pregnancy journey,” Tim says.

Lifestyle changes doctors recommend in the run up to conceiving

color image of sperm inseminated egg, life concept

There are a few recommendations that doctors suggest to help couples improve their chances of conceiving, Tim says.

Both men and women should:

Stop smoking — “Smoking reduces chances of conception for both men and women,” Tim says. “This is also true for e-cigarettes. You should try to avoid second-hand smoke as well.”
Reduce the amount of alcohol you drink — Tim recommends avoiding drinking completely ideally, or at least limiting the amount you drink to one to two units a week for women and four units a week for men.
Limit caffeine to one to two coffees a day.
Avoid excessive exercise.
Manage chronic conditions — Tim gives the examples of diabetes and thyroid disease, saying “see your healthcare team who can ensure everything is under control.”
Maintain a healthy weight — “Being underweight or overweight can affect your fertility,” Tim says. “Both men and women should aim for a BMI of 19-25.” This is because “women outside of this range may stop ovulating, and women with a BMI over 30 take longer to conceive. For men, not being a healthy weight can impact sperm quantity and quality.”
Think about the medicines you take — “Not all medicines you may be taking are safe if you’re planning a pregnancy,” Tim says, for both prescription and over-the-counter medicines.
Make sure your vaccinations are up to date — “This protects the future mother and developing baby from serious complications, while for men, it helps prevent bringing infections into the household,” Tim says. Although he notes that “Women should avoid getting pregnant for 1 month after having the MMR vaccination.”

Women should also do the following in the run-up to conception:

Take folic acid — Tim says you should take “(0.4mg) daily for at least 12 weeks before conception (and every day afterwards, up until you're 12 weeks pregnant).” This is because folic acid reduces the risk of babies having neural tube defects, such as spina bifida. Note that “you may be advised to take a higher dose of 5 mg if there is family history of spina bifida, you have diabetes, or you take certain medications,” he says.
Take vitamin D — take “10 micrograms of vitamin D each day, especially between September and March. The body makes vitamin D when it is exposed to sunlight, but during winter months, the body often cannot make sufficient vitamin D from sunlight alone,” Tim says.

A young African American woman takes her medication with a glass of water.

For men, there’s just one other thing medical guidelines say they should do before conception: avoid excess heat to the testes.

“Heat exposure can negatively impact sperm quality and motility,” Tim says. “Wearing loose-fitting, breathable clothing can help maintain a healthy temperature while also avoiding high-heat environments such as hot tubs and saunas, and prolonged sitting.”

What else can you to prepare for conception?

As well as the specifics above, Tim says that making more general health and lifestyle changes can also help.

“A diet rich in fruit, vegetables, whole grains, lean protein and healthy fats supports hormone balance, as well as egg and sperm quality,” he says.

“Sleep, exercise and maintaining a low level of stress are also all beneficial as they support hormone regulation and overall wellbeing.”

Men can also take a multivitamin, he says, just to make sure their bodies are “functioning optimally for healthy conception.”

Don't fall for expensive trimester zero hacks — it’s all about the basics

You might have seen influencers and biohackers doing more complicated things for trimester zero on social media, like reducing toxic exposure, doing red light therapy, lowering cortisol, or getting biomarker tests.

There is some merit in doing some of these things, but Tim says that they aren’t necessary. And the more experimental things, like red light therapy, “should be avoided,” he says.

“Most couples conceive without doing anything beyond the basics, and while lifestyle ‘optimisation’ can help, it’s not mandatory,” he says.

Trying to be perfect can create stress, guilt and pressure - none of which help conception. My advice is to focus on the essentials, and only add extras if they feel empowering, not overwhelming.

Dr. Tim Bracewell-Milnes, consultant gynaecologist at HCA Healthcare UK’s Lister Fertility Clinic

For example, when it comes to reducing toxic exposure, “Minimising things like smoking, heavy alcohol use and high environmental toxins (such as certain chemicals at work) is helpful,” Tim says. “However, it can be harder to control everyday ‘toxins’ such as plastic and cosmetics. For these, reducing exposure is fine if you find it straightforward and it doesn’t create stress.”

Lowering cortisol is more of a social media myth than anything else — cortisol spikes are a natural response to stress, and most people won’t have chronically high cortisol (that’s known as Cushing’s Syndrome and is different to chronic stress). But doing the things meant to lower cortisol, like exercise, meditation, and getting better sleep, can be beneficial to promote overall wellbeing.

Doing some testing can be helpful pre-conception. “The tests that may be beneficial are for sickle cell disease and thalassaemia,” Tim says, which are inherited blood disorders that mainly affect people with African, Caribbean, Mediterranean, south and southeast Asian, and Middle Eastern heritage.

“Pregnant women living in England will be offered screening tests for these disorders, but you don’t have to wait until you're pregnant to have a test, and it may be a good idea to get tested before starting a family if you or your partner are concerned,” he says.

What real mums did to prepare during trimester zero

Belly acupuncture

Tanya Griffiths:

“I heard the 3 months prior [to conception] were the most important, so I focused on them.

I cut out as much plastic as possible from food, switched all my non-stick pans to stainless steel, stopped heating food in plastic, cooked everything fresh from scratch, and also upped my calorie intake.

But the most significant thing was getting fertility acupuncture. I'd never done anything like that before.”

Gabs Caplan:

“I have mild PCOS and read that diet could help, so I moved to an anti-inflammatory diet when we started trying to conceive. I’m not sure whether it made a difference as didn't try for a baby prior to the diet change, but we did conceive within 3 months.”

Louise Hodges:

“I kept a little diary of any symptoms as my periods could be slightly unreliable, so it really helped. Other than that, I just took my normal vitamins, and I tried not to overthink it as I knew stress wouldn’t help.

We were incredibly lucky and only took 3 months to conceive. I really thought it would take much longer as I’d had previous problems with endometriosis.”

Vicky Laffan:

“I have unexplained infertility and so implemented many changes throughout the 8+ years (and IVF) that it took to conceive my little boy.

I took many different supplements, such as vitamin E, high dose vitamin S, choline, vitamin p, ubiquinol, folic acid, and pre-pregnancy vitamins.

I did fertility yoga, regular exercise, cut out caffeine and alcohol, did acupuncture, womb massages, guided meditations, tried to use as many natural, non-toxic products as possible. I also tried to cut out unhealthy snacks and improve my diet.”

Shelby Leanne:

“I didn’t with my first two, but I have recently cut out ultra processed foods and am trying to become more active and just generally having a healthier lifestyle. I have also introduced a prenatal vitamin in the hopes of possibly falling pregnant later this year!”

Katie Smart:

“I was trying for 4 years for my first and ended up down the IVF route. I cut down my tea consumption, took folic acid and vitamin D, made a conscious effort to eat more fish, and started acupuncture.”

Preparing for pregnancy doesn’t have to mean overhauling your entire life or chasing every wellness trend you see online. As Dr Tim Bracewell-Milnes explains, the idea of “trimester zero” is really about focusing on the basics: supporting your general health, making sensible lifestyle choices and giving your body the best possible starting point for conception.

For some couples, that might mean taking supplements like folic acid, improving diet and sleep, or cutting back on alcohol and smoking. For others, it might simply be checking in with a doctor about existing health conditions or medications.

But it’s also important to remember that there’s no such thing as a perfect pre-pregnancy routine. Many healthy pregnancies happen without meticulous preparation, and trying to optimise every detail can sometimes add unnecessary pressure.

Trimester zero isn’t a quest for health perfection — it’s about creating a supportive foundation for the journey ahead, one baby step at a time.

Authors

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Serafina KennyDigital Journalist

Serafina Kenny is a Digital Journalist at MadeForMums. She writes news and features and has expertise in health, nutrition, relationships, and history. She has previously written for Business Insider, Women's Health, Stylist, Men's Health US, The i Paper, Dazed, and more. You can contact her with tips and story ideas (or compliments!) at serafina.kenny@immediate.co.uk.