Being overweight affects your ability to conceive?

If you’re planning for a baby, or if you’re about to undergo fertility treatment, the first question you need to ask yourself is: ‘How healthy am I. Do I need to lose some weight?’ It’s an important question to ask because being overweight or obese when you’re pregnant puts your own health and your baby’s health at risk.

Being overweight affects your ability to conceive, for both men and women. Overweight and obese men have been found to have reduced sperm count and quality. Obesity can affect fertility in women by causing hormonal imbalances and problems with ovulation. It can also affect egg quality. Obesity is associated with polycystic ovary syndrome (PCOS), a common cause of female infertility.

Studies have found that being overweight and pregnant can increase the risk of miscarriage, gestational diabetes, high-blood pressure, pre-eclampsia and blood clots. It can also mean that your baby is more likely to be overweight and develop diabetes as they grow up. So, if you are trying to conceive, or want to start trying soon, be mindful of the fact that being overweight can affect your chances of conceiving and of having a healthy baby. Of course, how early you need to start losing weight will depend on how much weight you need to lose, but it is very important that you put in place a healthy eating and regular exercise plan that will help you to lose weight steadily, allowing you to enjoy a more comfortable pregnancy with less medical interventions. You will also be doing the best for your baby.

Body Mass index and obesity

Body Mass Index (BMI) is the calculation of a person’s height to weight ratio calculation. The simplest expression for this is the body mass index (BMI) calculated as weight (kg) divided by height in metres squared (m2). A BMI score below 18.5 means that a person is more than likely to be underweight, a score between 18.5-24.9 indicates a healthy weight, a score of 25 – 29.9 is above the ideal range and a score of 30 or more indicates obesity (to find out your BMI visit NHS choices 2015). Obese women are less likely to become pregnant through IVF and assisted reproduction. A BMI of over 30 (considered obese) has been shown to affect fertility and success with assisted reproduction by affecting ovulation and response to fertility treatment in terms of poor response to the stimulation drugs. Carrying excess weight is thought to affect how the ovaries function, due to changes in hormones and also metabolism.

Stress and weight gain

Unfortunately stress is a part of life, but it can also contribute to an increase of fat around the waist. In a stressful situation adrenaline helps you to get you alert and focused, whilst cortisol increases levels of fat and sugar in the bloodstream. The reason why fat targets your middle is because it is close to the liver where it can most quickly be converted back into energy if needed.

In order to manage stress though diet, eat little and often, and try to balance the protein, fat and carbohydrates in each meal or snack. Doing this will help to balance blood sugar levels which in turn will aid in managing stress and help to maintain your energy levels. Also, try to find out the best way of relaxing for you, whether it be a yoga class, a relaxing bath or a nice walk.

Stress busting nutrients

B vitamins

When stressed, our bodies use up B vitamins.  As these are our energy vitamins, low levels can leave us feeling fatigued. Eat lots of brown rice, quinoa, nuts seeds, green leafy vegetables, meat and fish.


Magnesium is another nutrient depleted during stressful times. Eat lots of quinoa, brazil nuts, oats, brown rice, legumes and leafy green vegetables.

Vitamin C

Low vitamin C levels decrease the activity of the immune cells that help fight bacteria and viruses, therefore keeping up your intake is especially important during times of stress. Eat lots of blackcurrants, citrus fruits, kiwi, strawberries, tomatoes, peppers and green leafy vegetables.


During times of stress our bodies need more protein as it helps to balance blood sugar levels, an imbalance of which can lead to a weaker immune system. Good sources include lean meats and poultry, eggs, pulses and oily fish like salmon.

Stress inducing foods to avoid:
Caffeine, sugar, salt, alcohol and fizzy drinks

Top nutrition tips to help manage your weight prior to conception or assisted fertility treatment.

  • Eat until satisfied, not full.
  • Watch your portion sizes (1 portion = 80g or the palm of your hand roughly).
  • Eliminate processed and sugary foods – instead, replace with nuts/seeds or fresh fruit or vegetable snacks instead.
  • Drink plenty of water to stay well hydrated, which can make you feel less hungry – aim for around 2 litres of water per day.
  • Eat a good balance of complex carbohydrates (to release energy over a longer period of time), protein and healthy fats.
  • Chew your food thoroughly.
  • Eat some prebiotic foods such as garlic, onions and leeks as these will feed the probiotic bacteria in the gut leading to a healthier digestive system.
  • Try to have a brisk walk each day for 20 minutes or more.
  • Choose a sport or exercise class that you like and try to stick to it.


Purcell, S. and Moley, K (2011). The impact of obesity on egg quality. J Assist Reprod Genet. 28(6): pp.517–524.

NHS Choices (2014)