Weight control can be problematic for some people at any stage of their life, but woman especially can have a tough time during pregnancy. Pregnancy can make you feel hungry nearly all the time, or send you running to the bathroom at the mere sight of food.

A new study carried out in Scotland looks at low and high body mass index (BMI) during pregnancy and the role it plays in the mother and child’s health as well as health care costs. They found that pregnant women who had too low or too high a BMI were at a higher risk for complications and additional hospitalization.

109,592 pregnant women were examined and classified in five categories based on their BMI. The classifications were:

- Underweight BMI < 18.5

- Normal BMI 18.5-24.9

- Overweight BMI 25-29.9

- Obese BMI 30-35

- Severely obese > 35

Researchers were able to show an association between higher BMIs and pregnancy complications. Severely obese pregnant women were 3 times more likely than normal-weight pregnant women to have high blood pressure and gestational diabetes. Compared to normal-weight women, those in all other weight categories had more and longer hospitalizations after birth. The risk of hospitalization was 8 percent higher for underweight women, 16 percent higher for overweight women, 45 percent higher for obese women and 88 percent higher for severely obese women.

The study also found that women with high or low BMI had higher medical costs than normal-weight women.

Co-author of the study, Dr. Fiona Denison of Queens's Medical Research Institute in Edinburgh, said in a journal news release, "Longer-term benefits of reducing maternal obesity will show improvements, not only in the health outcomes of mothers and their babies, but the workload and cost to current maternity services."

What does a BMI tell you about your health? Some experts say that determining a person’s BMI is the most accurate way to define a person’s weight on their health. Other experts believe that body-fat percentage gives a more accurate account.

If you are considering starting a family, there are many websites that offer online BMI calculators so you can find out what your personal BMI currently is.

If you are pregnant, discuss your weight with your obstetrician or family doctor to see how much weight gain is healthy for you personally. A regular BMI calculation doesn’t apply to pregnant women. You are supposed to gain a certain amount of weight while pregnant. Every woman will be different depending on her pre-pregnancy weight and over-all health.

Other studies have found an association between obesity during pregnancy and a higher risk of fetal complications. Women with a body-mass index between 30 and 35 were 58 percent more likely than those at a healthy weight to deliver an extremely premature baby, a team of U.S. and Swedish researchers found after examining the medical and delivery records of 1,599, 551 Swedish moms. Pregnant women with a BMI between 35 and 40 were twice as likely as normal-weight moms to have an extremely premature baby, while those with BMIs of 40 or greater were nearly three times as likely to deliver an extremely premature baby. 

The most important take-away from this study is that women who want to become pregnant understand the importance of maintaining a healthy weight prior to conception and continue to maintain a healthy weight gain during pregnancy.

Sources: http://www.sciencedaily.com/releases/2013/09/130918090847.htm

Linda Carroll, http://www.nbcnews.com/health/losing-weight-baby-moms-obesity-linked-extreme-preemies-4B11203812