Fertility Help – How Do BMI and Age Affect IVF and Fertility?

Eloise Edington  |   19 Nov 2020



We recently ran a poll asking what you’d like to know more about from our partner leading fertility specialists. The consensus was more information on age and weight when trying to conceive. With this in mind, we’ve turned to trusted fertility clinic, Clinica Tambre in Madrid, Spain who delve into optimal weight for fertility / IVF success and what age (ovarian reserve) means for fertility.

We want to know, how much does weight really affect fertility?

www.clinicatambre.co.uk | @clinicatambre



Why does body weight matter when trying to conceive? If you’re obese and trying to conceive, is it a worry?

Excess weight is one of the factors that affects conception the most.

Adipose (fatty) tissue also produces estrogen. Therefore, the more fat there is, the more the levels of these hormones increase in the body. What the brain does is to decrease the production of two hormones: LH and FSH, which are the ones that stimulate the ovaries. Consequently, the ovaries enter a state of rest and do not ovulate. And, without ovulation, no fertilization or pregnancy is possible.

Also, the higher the body mass index (BMI), the greater the chances of miscarriage in the first three months of pregnancy (the risk is very high when the BMI is over 25).

Weight can also affect a man’s fertility: it is known that adipose tissue produces inflammation that affects the quantity and mobility of sperm.

Related Article – Male Infertility – Calling all Fathers-In-Waiting – Everything You Need to Know about Male Infertility

Is it safe to lose weight whilst trying to conceive?

Losing weight whilst looking to get pregnant is recommended and safe, as long as it is done under the supervision of a (fertility) nutritionist and with a well-balanced diet, so that no nutrients are missing.

If you’re otherwise healthy, how important is your BMI when TTC?

The increase in BMI above 25 is related to a decrease in fertility and an increase in the first-trimester miscarriage rate.

For IVF, is a BMI of 30 (marking obesity) a cut-off for the NHS or is it proven science?

It is a cut-off that the NHS have determined, but that is related to the studies that are in scientific literature, which correlate BMI with the success of assisted reproduction techniques.

What are the consequences of a higher BMI in terms of stopping the embryos from implanting or anything else?

A high BMI is related to hyperestrogenism (increased levels of estrogens in the blood), which alters the ovarian response to ovarian stimulation medication and can also alter the quality of the endometrium (womb lining).

Does weight prevent people from being able to have IVF or IUI?

Excess weight and obesity can lower the success of IVF and IUI.

Related Article – Fertility Help – Clinica Tambre Answers your Questions on Covid-19 and Fertility


Exercise During IVF

What kind of exercise is advisable during IVF Stimulation and the two-week wait?

Gentle exercise is good, such as walking, yoga, swimming (pre transfer), etc.

High-intensity exercise and vigorous physical activity should be avoided during ovarian stimulation, as there may be a risk of follicle rupture, ovarian torsion and/or abdominal pain.

Is it possible that too much physical exercise can have a negative effect on fertility?

For women, intense physical exercise can lower reproductive capacity because it can cause disorders like amenorrhea (absence of menstruation), which indicates the absence of ovulation and with that the impossibility of becoming pregnant.

For men who do very intense physical exercise and consume steroids or anabolic agents, this can sometimes reduce the testosterone hormone levels, as well as diminishing the size of the testicles and the number of sperm, therefore causing male infertility.

Related Article – IVF – What is PGT and is it Necessary? Clinica Tambre Answer your Questions

Ovulation and Anovulation

In your twenties, how long is it likely to take to ovulate, having just come off the pill?

Most women without health problems in their twenties ovulate correctly in the first cycle after stopping the pill. Studies show that in the following three cycles, 98% of women have ovulated.


Ovarian Reserve and Age

Is it possible to improve your ovarian reserve without hormone injections?

The ovarian reserve unfortunately cannot be improved by drugs or lifestyle changes because it is something that is genetically determined.

Related Article – Fertility Help – Are my Eggs Diminishing in Number as I Approach 35?

When you have a low AMH level, how can you improve egg quality and health?

In cases of low ovarian reserve, the only thing we know is that ovarian quality is closely related to age.

Clinical studies have shown that adopting a healthy lifestyle and adding specific fertility supplements, such as antioxidants and vitamins increases the percentage of eggs that develop into good quality embryos.


Why do miscarriages occur more often?

Miscarriage has increased mainly because of the rising average age at which women begin to seek pregnancy, which is above 30 years in almost all European countries. The increase in maternal age is the main cause of genetic abnormalities in embryos, which in turn is the main cause of miscarriage. Before the age of 30, the risk of suffering a miscarriage is less than 10%, whereas after the age of 42, the risk is almost 75%.

In recent years, there has also been an increase in maternal pathologies related to miscarriage, such as diabetes, thrombophilia, antiphospholipid syndrome and hypertension. Excess weight or malnutrition also play a role. From the male point of view, there are studies that show that exposure to toxins from work or excessive consumption of coffee, tea and chocolate can cause alterations in the sperm that can increase the risk of miscarriage.

Related Article – .Baby Loss Awareness – What Not to Say to a Woman Who’s Had a Miscarriage

What advice do you have for someone trying to conceive at 40 or older?

From 40 onwards, the quality and quantity of the eggs is worse and this leads to a decrease in fertility. The chances of achieving a natural pregnancy are much lower so, if pregnancy is not achieved, it is advisable not to wait more than 6 months before consulting an assisted reproduction clinic.

In addition, after 40 the risk of complications is greater, so it is very important to control all modifiable risk factors such as diet and lifestyle to try to reduce all other risks. Weight control is very important because it is related to an increase in hypertension and gestational diabetes during pregnancy, which are two more frequent pathologies in women over 40.

A big thanks to Clinica Tambre for their insightful answers to these topical questions on the effects of age and weight on IVF / fertility. If you’d like to find out more from their fantastic team of experts, you can message them here. They are operating as normal during this Covid-19 era and consulting virtually.

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