Three in every 100 women find themselves pregnant with twins, up from a rate of one in 100 only a generation or two ago.
Twins, Advanced Maternal Age & Fertility Treatments
There are several reasons why multiples pregnancies are on the rise. With more and more women delaying pregnancy well into their 30s and 40s, the incidence of non-identical (also known as fraternal or dizygotic) twins or triplets has boosted, thanks to age-related hormonal changes which can cause [tooltip text="Hyperovulation is the release of more than one egg during a single menstrual cycle"]hyperovulation[/tooltip]. The increased use of fertility drugs and in vitro fertilization also greatly contributes to the increased rate of twinning currently observed.
Predisposition for Multiple Births
While there are no factors that seem to increase your chance of having identical (maternal or monozygotic) twins — those conceived from one fertilized egg which splits into two embryos – your chance of conceiving non-identical (fraternal) twins is increased if there is a history of fraternal twins among women in your family. Twins are also more common in black women than white women, and less common among Asian and Hispanic women.
Diet Can Increase Chance of Twins
Some research indicates that folic acid supplementation — which is currently recommended for all women of childbearing age — may contribute to an increased chance for twins.
Diagnosing Twins: Could It Be Two Babies?
Exaggerated Pregnancy Symptoms May Suggest a Multiples Pregnancy
Mothers of multiples may find that they experience increased or exaggerated early signs of pregnancy such as more severe morning sickness, indigestion, edema, increased weight gain, and large-for-date uterine size. However, these symptoms can all occur in a normal, healthy, singleton (one fetus) pregnancy.
Blood Tests May Suggest Twin or Triplet Pregnancy
Abnormal prenatal AFP (Alphafetoprotein) screening blood tests may also suggest a multiples pregnancy, as can elevated HcG (Human Chorionic Gonadotrophin) levels in blood or urine tests very early in pregnancy.
More Than One Heartbeat
If your doctor or midwife suspects you may be carrying more than one baby, she or he may look for and detect more than one fetal heartbeat using a fetal doppler machine. Keep in mind, however, that the heartbeat of a single fetus can be heard from more than one location, meaning that this method only confirms twins, triplets (or more) if the heartbeats detected differ in rate. For this reason, the auditory detection of “multiple” heartbeats alone is rarely used to diagnose a multiples pregnancy.
Ultrasound Tests Can Confirm Multiple Gestations
With the advent of modern technology and prenatal care that includes ultrasounds, nowadays twins are rarely a birth day surprise and are almost always diagnosed well before delivery, during the first or second trimester of pregnancy; a multiples pregnancy is definitively confirmed with ultrasound, where sound waves are used to create actual images and/or video of the uterus, placenta, and baby or babies.