MANILA, Philippines - Several myths about pregnancy just won't go away. For instance, most people continue to believe that having sex while pregnant harms the baby when medical studies have shown otherwise.

Dr. Phil McGraw, popular author and television personality, tells us what's true and what's not when it comes to pregnancy.

In his website, Dr.Phil.com, McGraw lists common myths and truths involving pregnant women with the help of Yfat Reiss, co-author of How to Make A Pregnant Woman Happy:

MYTHS

Pregnant women crave pickles and ice cream. Not all women crave pickles and ice cream, but McGraw said food cravings such as these are based in fact. In general, he said food cravings can be very helpful in determining what a pregnant woman's body needs. For instance, some women may crave pickles because they are sodium deficient, while others want ice cream for comfort.

Pregnant women who carry low = boy, or pregnancy acne = girl. The shape and the height of the belly cannot indicate a baby's sex, McGraw said. Instead, women tend to carry lower or higher depending on their body type. He added that pregnancy acne has nothing to do with a baby's sex -- it's only a result of natural hormonal changes.

Pregnant women must eat for two; they must gain 25 pounds. As long as a pregnant woman eats properly -- and as long as her doctor is not concerned -- McGraw said there is no set formula on how much she must gain.

Pregnant women shouldn't take baths. They can, but McGraw said they should stay away from hot baths because water over 98 degrees Fahrenheit (or 37 degrees celsius) is unfavorable to the pregnancy.

Pregnant women shouldn't eat fish. Although women are told not to eat fresh fish due to mercury levels and fears of food poisoning, McGraw said women can choose fresh fish with low mercury levels. After all, he said women in Japan don't stop eating sushi. (Click here to know the mercury content of fish and some seafood)

All pregnant women have morning sickness. McGraw said the feeling of morning sickness is often caused by a rise in the female hormone estrogen during pregnancy. If the pregnant woman's body already produced a high level of estrogen prior to her pregnancy, McGraw said additional estrogen may cause morning sickness in the first trimester.

TRUTHS

Pregnant women shouldn't change cat litter. Toxoplasmosis, a virus in cat feces, can be very harmful to the pregnancy, according to McGraw. Given this, he said all contact with cat litter must be limited and the house must be kept extra clean.

Pregnant women should not carry heavy items. Specifically, McGraw said a pregnant woman must not carry things weighing more than 25 pounds since her body is already burdened by additional weight.

Pregnant women shouldn't drink alcohol. McGraw said alcohol is "feto-toxic," which means it is poisonous to the growing baby -- one drink a day can create a noticeable problem in the pregnancy.