DEAR DOCTOR K: I just found out I'm pregnant with twins. How will this pregnancy be different from my last one?
DEAR READER: Congratulations! Along with double the diapers and late-night feedings, you'll experience double the love, laughs and fun. But, yes, you will have to deal with some challenges.
In the United States, twins occur in one out of every 35 births. Twins can be fraternal or identical. Fraternal twins occur when two eggs are fertilized. This produces two embryos; they are not identical, and may not even be the same gender. In fact, fraternal twins are genetically no more similar than other siblings.
In contrast, identical twins develop from a single egg that cleaves, or splits, after it is fertilized. The two halves of the cleaved egg separate, creating two embryos that are genetically identical.
A multiple pregnancy differs from a singleton pregnancy in several ways. For example:
-- Pregnancy symptoms, such as morning sickness and breast enlargement, may be more severe.
-- You'll gain a substantial amount of weight. Pregnancy is the one time in most women's life that a doctor suggests that they gain weight. You'll be advised to gain between 35 and 45 pounds if your weight was in the normal range to start with. Many doctors recommend gaining an average of 1.5 pounds per week during the second and third trimesters.
-- Symptoms of later pregnancy may occur earlier and be more severe. Your heavy, stretched uterus will place pressure on your organs. This may cause fatigue, shortness of breath, heartburn, constipation, pelvic discomfort, urinary leakage, back pain and hemorrhoids.
-- Complications are more common. These include pre-term labor, premature rupture of the amniotic membranes, pre-eclampsia, placenta previa, prolonged labor and newborn problems.
-- You'll have a higher chance of premature delivery. Many twins are born at 37 to 38 weeks of gestation.
-- Twins are more likely to be born with low birth weight (less than 5.5 pounds).
-- You'll be at increased risk for developing anemia due to deficiencies of iron and certain vitamins. That's why women carrying twins are prescribed relatively high doses of iron and folic acid supplements.
-- You'll also be at increased risk of developing high blood pressure and high blood sugar during pregnancy, a fatty liver, and blood clots in the veins of your pelvis and legs. Having said this, these complications are still unusual and can be treated.
Your doctor will use ultrasound throughout your pregnancy to monitor the growth and development of the fetuses. Ideally, both babies should have similar growth and weight gain.
Ultrasound also provides valuable information about the position of the fetuses. This information is especially important at the time of delivery. It can help determine whether it will be safest for you to deliver vaginally or by cesarean section.
So this pregnancy may well be more challenging than previous pregnancies. But you'll have two wonderful children.
Dr. Komaroff is a physician and professor at Harvard Medical School. To send questions, go to AskDoctorK.com, or write: Ask Doctor K, 10 Shattuck St., Second Floor, Boston, MA 02115.