Vanishing Twin SyndromeDeborah Bohn
“We won the conception lottery!”
That’s what I wrote in my online journal when I found out that my husband and I were expecting twins. After months of hormone injections, blood tests, ultrasounds, pills, ovulation test kits and egg extraction procedures, plus a heartbreaking miscarriage, we had finally hit the baby jackpot with the help of a fertility specialist and in vitro fertilization. The ultrasound image at my eight-week check-up showed two shrimp-like embryos and two little heartbeats flashing on the screen. My gynecologist gave me the phone number for a twins support group and told me to get ready for a wild ride!
Imagine my shock and horror when the next ultrasound, a mere two weeks later, showed one fat, wriggly embryo and one tiny bean-shaped one with no heartbeat. We were devastated. Grief stricken. How could this have happened? What went wrong? And what was going to happen to the surviving fetus?
The doctor said I was experiencing Vanishing Twin Syndrome, a common occurrence in the early stages of a multiple pregnancy. I might feel some cramping and possibly a tiny bit of bleeding, but the healthy baby would most likely survive and the “little one,” as we called it, would be reabsorbed by my body over time and simply…vanish.
He was right. Although we were emotionally devastated by the loss of our tiny unborn baby, there was no discomfort or bleeding. My 20-week ultrasound revealed a healthy fetus and an empty amniotic sac, but no sign of the little twin. Our daughter was delivered healthy and on time, but we still think about what it would have been like to raise twins. We still sometimes miss the baby that came and went like a little ghost.
Act of Nature
As strange as it sounds, vanishing twins are pretty common. Before the advent of early ultrasounds, women didn’t realize they were carrying multiple babies until the heartbeats could be heard at 12 weeks or until their regular five-month ultrasound. If two embryos had been conceived and one lost during the first trimester, a mother would never have known it.
Experts currently estimate that one-eighth of pregnancies begin as twins. But of course, the percentage of pregnancies that make it to term is smaller. Fertility specialist Dr. Carolyn Givens of the Pacific Fertility Center estimates that between 15 and 20 percent of all twin pregnancies will miscarry one fetus. “That’s what happens what happens with a vanishing twin,” she says, “You have an early miscarriage of the twin.” Those estimates are supported by a 1986 sonogram study of 1,000 pregnancies. Exactly 21.9 percent of the women carrying twins in the first trimester experienced a “vanishing twin” event. Due to the increased use of fertility drugs and assisted fertility techniques like in vitro fertilization, there’s been a spike in multiple pregnancies and an accompanying rise in early gestation ultrasounds, so what used to be an almost unheard of phenomenon is rapidly becoming a hot topic among mothers.
When our twin disappeared, I found myself wondering if I’d done something wrong to cause the embryo to die. Did I sleep in the wrong side? Inhale someone’s second-hand smoke? Lug my heavy one-year-old daughter around too much? The fact is that most of the time a twin vanishes during the first trimester for the same reason a single baby miscarries: There’s a fatal genetic problem with the embryo and it couldn’t continue developing into a full-fledged fetus. Dr. Givens explains, “This usually happens within the first eight weeks because that’s when the organs form, and if there’s a problem, this is when it will occur. If there’s a chromosomal problem, some important gene doesn’t turn on or do what it’s supposed to do and the heart will stop developing.”
However, older mothers tend to experience vanishing twin losses more frequently. “Spontaneous fraternal twins are more common in older moms because they ovulate more than one egg more often. And older women have a higher rate of miscarriage because of chromosomal abnormalities,” Givens says.
Unlike the miscarriage of a singleton, a woman is less likely to have bleeding with a vanishing twin because the healthy embryo keeps generating hormones to keep the placental lining in place for nourishment and protection. That’s why many women have no idea the second twin even existed. There were no obvious signs that it was ever there and no physical indications of a problem when it died. While there is “minimum physical risk to the mother if it happens in the first trimester,” according to Dr. Givens, there is a small (less than 10%) chance that the healthy baby will be lost at the same time. In that event, both embryos would be washed away in the blood of what appears to be a heavy period, but is actually an early stage miscarriage.
Tragically, just like some singleton babies are lost in the second or even third trimesters, the same goes for twins. But the risks to the mother and surviving baby are much greater in the case of a multiple pregnancy. When a single baby stops growing, the body either expels the fetus, resulting in a miscarriage or a stillborn baby, or a doctor removes the tissue for the safety of the mother. But when a twin is lost late in a pregnancy a few different things can happen.
“If you lose a twin after 20 weeks, you are at a much higher risk to lose the other one. There’s so much tissue present that the body wants to expel it and take the live one with it,” Dr Givens explains, “The major risk to losing a twin when the other isn’t ready to be delivered, is the prematurity of the surviving twin.”
On the other hand, if non-living tissue remains in the uterus, the mother is at risk for coagulation problems caused by proteins from the tissue releasing into the mother’s bloodstream. This can cause a condition called Disseminated Intravascular Coagulation that rarely can lead to complications that can result in the death of the remaining baby. If you are in this unusual situation, a specialist will monitor you for changes.
In extremely rare cases, a late-term twin actually vanishes too. Sometimes the water from the non-viable fetus is reabsorbed into the mother’s body, but the weight of the surviving twin compresses the remaining fetal tissue and forms a “fetus papyraceus”—a flattened, paper-like thickening in the wall of the amniotic sac, which can only be seen after delivery.
The Emotional Toll
In my experience–and everyone’s is different–Vanishing Twin Syndrome is like simultaneously hosting a birthday party and a funeral in the same room. You’re thrilled and relieved that you’ve got a healthy baby growing bigger and stronger, while you’re mortified that you’re carrying a dead baby in your belly and heartbroken by the loss of a child you longed for so desperately. As a fertility specialist, Dr. Givens sees a large number of initial multiple pregnancies that ultimately result in a single live birth. She says, “Prospective parents generally have mixed feelings when they lose a twin. In the fertility world, a lot of times people don’t have kids, this is their first pregnancy, and the loss is almost universally a sad thing for them. But it depends on whether they really wanted twins to begin with. Sometimes couples are a little relieved if they already have children and don’t want twins. Either way we tell them that the twin wasn’t healthy, so the loss was actually a positive thing, although it might not feel that way at the time.”
Could You Be a Twin?
Could you be the surviving half of a twin pregnancy? Could you have been pregnant with twins and not known it? As reported by Lawrence Wright in The New Yorker, Professor Charles E. Boklage, a developmental biologist at the East Carolina University School of Medicine and a well-known twinning expert says that Vanishing Twin Syndrome “is much too common to be considered phenomenal, and it occurs for too many reasons to be considered any kind of syndrome.” He contends that since most pregnancies fail in the early weeks—often unbeknownst to the mother—the early loss or disappearance of a twin is to be expected. Dr. Boklage estimates that for every set of live twins there are at least six singletons who are survivors of twin conceptions. He says, “Somewhere in the vicinity of ten to fifteen percent of us—and that’s a minimum estimate—are walking around thinking we’re singletons when in fact we’re only the big half!”