Or to be more precise, a woman has 3.3 percent chance of conceiving twins naturally. By naturally, we mean without any kind of fertility treatment.

A woman who was at a healthy weight before becoming pregnant will on average gain 25-35 pounds. This can be calculated of gaining 1-5 pounds during the first twelve weeks and a subsequent pound per week for the remainder of the pregnancy.

Blood tests are done in a doctor's office. They can pick up hCG earlier in a pregnancy than urine tests can. Blood tests can tell if you are pregnant about six to eight days after you ovulate.

Since your baby's most critical development has taken place by month 3, your chance of miscarriage drops considerably after three months.

Avoid exposure to toxic substances and chemicals, such as cleaning solvents, lead and mercury, some insecticides, and paint. Pregnant women should avoid exposure to paint fumes.

Most women hit their fertile peak between the ages of 23 and 31, though the rate at which women conceive begins to dip slightly in their late 20s.