Finally we have proof! Doctors often misinform parents about zygosity

Throughout my pregnancy, my OB and the ultrasound technician told us our boys were absolutely, positively, no-doubt-about-it fraternal. Yes, my doctor said, identicals can have separate placentas and sacs, but mine implanted too far apart to be identical.
Their placentas were on polar opposite sides of the uterus.
Identical twins implant more closely, he said.
He was wrong.
And he has company.
In a new study from University College London, researchers found that doctors wrongly told parents their identical twins were fraternal in 27.5 percent of the cases. Like my guys, those twins had their own sacs and placentas.
The study also found that 2 percent of parents were wrongly told their fraternal twins were identical because doctors did not realize their separate placentas had fused into one. Overall, 15 percent of twin parents were misinformed about zygosity.
I have long suspected the statistics involving identical twins are skewed.
This proves it.
So many parents find out long after birth that their twins are identical through DNA testing. That information is never reported to any statistic-gathering source. If this study hold true in the US, then statistics showing the odds of having identical twins is about 3 in 1,000 are way off.
It has become a game on online twin forums: Guess whether the twins are identical while the parents await results of DNA testing. In most every case where parents of di/di had trouble telling their twins apart, the results showed they were, indeed, monozygotic, or identical.
I have come across just as many parents of look-alike twins in real life and virtually who decline testing despite their gut feelings. Either they can't afford the $100 to $200 fee or they see slight differences between their twins and accept those as evidence their twins are fraternal.
We could have done that do that with our guys.
Matthew has a slighter build and a thinner face. Jonathan is much more muscular and has a rounded face -- a little more body fat in his cheeks. But that scenario is true of most identicals. One usually has a slightly different facial shape than the other.
In some of those cases, parents brushed off their identical suspicions because their hospitals "tested" the placentas and the results showed they were dizygotic, or fraternal.
Our own doctor fell for that until I pressed him for more information and he checked with the hospital.
It turns out hospitals check only whether placentas are fused. The hospital techs either definitively declare the zygosity according to the results or the pass the results on to doctors or midwives who were told in medical school that two placentas equals fraternal.
The doctors or midwives then pass that misinformation on to parents.
Remember this: hospitals DO NOT do DNA testing.
In the defense of OBs, midwives and ultrasound technician, zygosity is irrelevant in caring for pregnant women. What matters is only whether there is one placenta or two, and one sac or two. So they really don't need to know for medical purposes.
That doesn't, however, excuse the giving of misinformation.
In our case, a fellow soccer mom who was a neonatologist educated me.
She told me that identical twins implant separately when the split occurs immediately after conception -- within the first few days. Matthew and Jonathan probably became two far up in the fallopian tube, she said, allowing them to fall and implant independently, just like fraternal twins.
At the very least, our OB should have told us he didn't know.
He should have known that he didn't know.
All doctors, midwives and ultrasound technicians should know that they can't be certain with same-gender twins until after the babies are born. Though the information is medically irrelevant during pregnancy, there is no excuse for being misinformed about something so relevant to the field in general or for passing that information on to parents.
None.

Two-year stats

Not all identical twins develop identically in their physical growth.
Just last week, I met identical twin girls at the local mall with their mom. The girls were 3 years old and one was more than an inch taller than the other. The difference, the mom said, was likely caused by twin-to-twin transfusion, which forced doctors to deliver them at 27 weeks or lose the smaller twin.
Our guys were lucky.
Each had his own sac and his own placenta. Their placentas were on polar opposite sides of the uterus. It can't get better or safer than that. Their placement in utero was so rare that it took DNA tests to persuade my OB that they are, indeed, identical.

So I wasn't surprised by the findings at their 2-year physical:

Height: Both boys are 37.5 inches tall, landing them off the charts compared to other boys their age. Our two older children are off the charts for height as well. It's in their genes. Their dad looms 10 inches above me at 6 feet, 5 inches tall.

Head: Their measurements were precisely the same even though most folks insist that Jonathan's head is bigger. Jonathan has slightly more fat in his cheeks than his brother. I sometimes wonder if that is because Jonathan was born via c-section while Matthew experienced a vaginal birth. It's not likely, but it's something to think about.

Weight: Matthew was the lighter of the two at 31 pounds, 4 ounces. Jonathan weighed in at exactly 32 pounds. It might be the cheek fat. It might have been a wet diaper. It might have been because Matthew takes so much more pleasure in throwing his food than in eating it. Who knows?

Overall, the doctor proclaimed Jonathan and Matthew healthy, but she referred them to specialists for speech and hearing. Though the county program denied them services, she felt their reluctance to use more than one syllable per word and their refusal to put to words together is probably the source of unnecessary frustration.
She figures twinese is the cause, but that a little therapy might make life better for all of us.
I have to agree.
So off we go to Children's Hospital.
We'll be checking back with the pediatrician in six months.
Hopefully, by then, we'll be asking for advice on how to tune out their constant chatter.