Calculate your BMI

It is important to accept that you are going to put on weight during pregnancy. You are meant to because your body is growing and changing to give your baby the best start in life. The amount of weight you should gain will depend on how heavy you were before you became pregnant, or more accurately, on what your body mass index (BMI) was before pregnancy.

Our pregnancy weight gain calculator can give you an indication of what you might gain.

The chances of conceiving are much better when women are in their healthy weight range. Being overweight (body mass index [BMI] of over 26) can affect ovulation (egg production), because it increases women's hormone levels. It can also increase the risk of complications like pre-eclampsia and diabetes during pregnancy. Being overweight can reduce sperm production in men.

Being underweight (BMI of under 18) can reduce hormone levels, stopping periods and ovulation, and there is a possibility of having a low-weight or premature baby.

How to work out your BMI

- The hard way:
Take your pre-pregnant weight (in pounds) and divide it by your height (in inches) squared; then multiply by 700.  BMI = lb/in squared x 700.
For example, if I weigh 110 pounds and am 60 inches tall,   my BMI is 110/3600 x 700 = 21.4

- The easy way - use the calculator below:

Enter your weight [in pounds or kilograms] and your height [in inches or meters] in the form below

Height	in orm	»»»	your BMI =
Weight	lb orkg
Age (optional)	years	»»»	Age-corrected BMI =
			The correction for age is a purely mathematical (not clinical) extension

The BMI is calculated and interpreted as follows:

BMI Below 18.5 is Underweight,     BMI = 18.5 to 26 is Normal - Ideal,
BMI = 26 to 30 is Overweight,         BMI 30 to 40 is Obese.
BMI greater than 40 - Severely Obese

It is recommended that women should aim for a weight gain related to their pre-pregnancy BMI:

• If BMI was above 26, you should aim for a weight gain of between 15 and 25lb (7 and 11.5kg).
• If BMI was between 20 and 26, you should aim for a weight gain of 25 to 35lb (11.5 to 16kg).
• If BMI was less than 20, you should aim for a weight gain of 28 to 40lb (12.5 to 18kg).

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Our pregnancy weight gain calculator can give you an indication of what you might gain.

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Weight Conversion	Height Conversion
Metric Kilogram Gram Avoirdupois (U.S.) Stone Pound Ounce	Metric Meter (m) Centimeter (cm) British And American Foot (ft) Inch (in)