Getting pregnant > Considerations before conception > Your health and fertility > Does my weight affect my chances of conceiving?

Does my weight affect my chances of conceiving?

We look at how your weight influences your fertility and affects your chance of getting pregnant
For many of us weight is a very sensitive subject and as we're all built differently there is no definitive answer to this question. Instead, it's all about what's right and 'normal' for you.

Regardless of your weight if you experience regular menstruation every 28 days or so its likely that you'll be ovulating regularly too which is of course essential for baby making. However, if you are very under or overweight there is still a chance that your fertility could be affected.

Am I the 'right' weight?

Body Mass Index (BMI) is the measure of weight currently favoured by many health professionals. It takes into consideration your weight in relation to your height and while this method isn't flawless (it doesn't take into consideration the ratio of fat tissue to muscle mass) it is a reasonably reliable predictor of whether you are currently in a medically healthy weight range.

You can work out your BMI by:
  • Dividing your weight in Kilograms by your height in meters
  • Then, dividing the answer by your height again
  • The result will be your BMI
Alternatively, the nhs offer a free BMI calculator on their website - Click here to visit the site.

If your BMI is:
  • less than 18.4, you are underweight for your height.
  • between 18.5 and 24.9, you are an ideal weight for your height.
  • between 25 and 29.9, you are overweight for your height.
  • between 30 and 39.9, you are obese.
  • over 40, you are very obese.
Overweight and trying to conceive

If your BMI is above the ideal weight for your height it is possible that there will be some implications for your fertility. Research has found that being significantly overweight can cause hormone imbalances that result in issues such as polycystic ovary syndrome and sub-fertility (where it takes longer than 'normal' to conceive). Additionally, excess weight has also been found to reduce the effectiveness of fertility procedures such as IVF.

There are also weight implications to consider once you fall pregnant as significantly overweight women are more likely to experience complications such as gestational diabetes, preeclampsia and birth difficulties than those who are within their healthy BMI range.

It's not to say that if you're carrying a little excess weight you won't fall pregnant as we're all made differently and there is no one ideal weight. However, it may help your chances of falling pregnant sooner if you make a few lifestyle changes that help you to drop a few pounds. Dieting whilst trying to conceive is fine as long as you don't restrict your calorie intake too severely or limit your intake of certain food groups. Instead you should focus on eating a healthy, balanced diet, drinking plenty of water, cutting out alcohol and getting some exercises - just half an hour of walking, yoga or swimming a day is a great place to start.

If you are overweight and having difficulty conceiving you should visit your doctor as they will be able to eliminate or treat any underlying medical conditions and advise you as to the best course of action.

Underweight and trying to conceive

If your BMI is below the ideal weight for your height it is also possible that your chances of conceiving may be affected. For instance, if you severely restrict your calorie intake or exercise very heavily you may either continuously or periodically suffer from amenorrhea. This is the absence of both periods and ovulation, a condition which will make it very difficult to conceive. Amenorrhea can happen because you have so little fat on your frame that your body goes into 'starvation' mode and the delicate hormonal balance that signals the development and release of healthy eggs from your ovaries is disrupted.

There are also implications if you are severely underweight when you fall pregnant. For instance, lower than healthy maternal pregnancy weight has been associated with both preterm delivery and low infant birth weight, neither of which are ideal. Additionally, if you heavily restrict your diet you may also deprive your body of the essential nutrients your baby needs for healthy development which can cause different problems.

If you are significantly underweight and struggling to conceive it is worth visiting your doctor for advice in case of any underlying medical issue. However, you may also like to try increasing your calorific intake, focusing on eating a balanced and nutrient rich diet and taking exercise in moderation.

Do you worry that your weight might affect your chances of conceiving? Whatever your concerns visit the AskBaby Forums and share your advice, questions and support with other parents-to-be.

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im over weight dose this mean i will never have a baby
by dogooder 16th Jan 2009, 9:44am