Foam on the grass

Sometime in the moments after my OB, staring at the ultrasound screen, softly uttered the words that are frozen in my brain—I’m afraid it means the baby has died, in answer to my question of what it meant that there was no heartbeat—she turned to me and said reassuringly, assuredly, that most women who experience stillbirths go on to have living babies; having more than one stillbirth is incredibly rare, even more rare than having just one. (Oddly, she never actually used that word, stillbirth; I had to put it together myself after I began to grasp that I would still have to go through labor.)

The MFM doctor we were whisked to immediately after, to confirm that Luke had died, said much the same thing: To have multiple stillbirths is extremely rare. Many women go on to have normal pregnancies? I asked him. Most do, he replied.

Sometime in the weeks after Luke’s death, I read another baby loss mom’s blog about being treated as “low risk high risk” by the staff at her MFM; her second child had died of an umbilical cord knot. She was pissed about being treated this way, but I remember thinking, OK: Low risk high risk—I can live with that; I like the sound of “low risk”; that lessens my anxiety.

And I saw the statistics. About 1 in 160 pregnancies (0.5 percent) end in stillbirth, defined in the U.S. as a loss after 20 weeks of gestation. Of those stillbirth moms, fewer than 1 in 100 have more than one stillbirth. You probably won’t get hit by lightning twice. And I have a healthy daughter, who was born at almost exactly 40 weeks after an uneventful pregnancy. Plus, on the way to the hospital, we saw rainbows by the side of the road, twice, and days later I learned the term rainbow baby means a child born after a loss. And so, from somewhere deep in the dark grief, a little kernel of hope sprouted.

All of that was robbed from me the day I received the autopsy results.

In the medical literature, massive perivillous fibrin deposition and its associated conditions are described with bluntly dire language such as “high recurrence,” “severe consequences for the fetus,” and “associated with stillbirth” and a host of other issues including miscarriage and intrauterine growth restriction. In the face of such odds I questioned whether I should even try to have another child. On top of so many other secondary losses (friendships, my job, my innocence), it was devastating to think another pregnancy might not be in the cards.

Then in early January, we went to see Dr. Harvey Kliman, a placental pathologist at Yale, to talk to him about his review of our placental sides, and a teeny, tiny seed of hope was reborn.

How a placenta normally functions

As Dr. Kliman explained it, one of the placenta’s many roles is “to immunologically appear to be invisible to the mother”: to protect the fetus, via cells known as trophoblasts, from attack by the mother’s immune system. Otherwise, the maternal immune system would reject the baby’s foreign tissue in the way that it would attack tissue transplants from an incompatible donor.

Dr. Kliman noted that the ability to distinguish self from non-self is an evolutionary advantage predating life on land by hundreds of millions of years, and that even single-celled sponges, if mixed together, will separate back out into themselves—”they know what is me and what is not me.”

Why placentas occasionally fail in this role is poorly understood because scientists don’t yet understand how a normal placenta is able to function in this immunologically invisible way. In the 1950s, Medawar described this as “the paradox of pregnancy”: the puzzle of why most animals, and humans in particular, don’t reject their pregnancies. As Dr. Kliman said, “We have this pregnancy inside of a woman when really everything that’s made about her is designed to not let that happen.”

From four weeks on, the developing embryo and its support organs take on a structure that can be likened to a plant: the embyro is the plant, the maternal blood is the soil, and the placenta is the root system, with the “soil” circulating between the root fingers, known as villi.

The maternal blood is in constant contact with the villi, much like water circulating around your fingers if you put your hand in a bucket of water. Crucially, one of the trophoblast cells’ many functions—in addition to manufacturing steroids, absorbing nutrients, and expelling wastes—is to prevent this blood from clotting, like deicing a wing; “there’s constantly deicing going on,” Dr. Kliman said.

The grass analogy

Some trophoblasts also leave the placenta, enter the maternal blood circulation, and destroy the walls of the maternal blood vessels in order to open them up and allow for more blood flow. In some cases, for genetic reasons the trophoblasts don’t perform this function, resulting in such low flow to the placenta that the tissue actually dies.

Dr. Kliman compared this to grass dying after a sprinkler system is shut off. “You have brown grass, but you have nothing in between the grass.” In Luke’s case, he said, there was “foam on the grass”: the fibrin, or clotting material, that built up in the placenta. Not only was the placenta infinitesimally small, at the 0.01 percentile (meaning smaller than 99.9 percent of the placentas in his age group), it was only 5 percent functional.

“This is not turning the sprinkler off,” Dr. Kliman. “This is, someone has covered the whole grass with a foam that doesn’t let any light in, no water, and the little leaves are just stuck in this gluelike stuff. … The intervillous space was just obliterated in this placenta. There were very few places for the mother’s blood to interact with the fingers.”

On the slides, Dr. Kliman noted that the villi had branched in an effort to obtain more surface area and more contact with my blood, in the way that a plant growing in low light will become long and spindly. He also found evidence that Luke, incredibly, had made his own blood cells in response to lower oxygen delivery. “I think that’s just a testament, if you will, to how healthy he was, in the sense that even though he was in such an adverse environment, he really managed to survive so well for so long.”

Luke was also abnormally large compared to the size of his placenta; a normal fetus-to-placenta ratio is 6:3, and his was 7.8:1. Despite his tiny placenta, Luke himself was still in the 10th percentile. “I think it’s an amazing thing that he made it that far,” Dr. Kliman said.

Villitis versus intervillositis versus MFI

Dr. Kliman also clarified the diagnosis as MPFD/CHI. Whereas the pathology report from the hospital had referred interchangeably to MPFD and maternal floor infarction, the latter signifies fibrin deposition confined to the maternal floor, or the area where the placenta attaches to the uterus, whereas in Luke’s case fibrin was found throughout the placenta.

He clarified the difference between conditions associated with MPFD. In villitis of unknown etiology, the villi themselves are attacked by the mother’s T-cells, the tissue-recognizing cells that reject foreign tissue. While there was a little of that happening in Luke’s case, Dr. Kliman said he believes it to be closer to intervillositis, an attack on the cells between the villi. All these conditions are part of a spectrum, and while it wouldn’t seem to matter which specifically I had, it’s important to note that villitis can be treated with immunosuppressive therapy, whereas intervillositis cannot.

Because I have a healthy daughter who delivered normally at 40 weeks, Dr. Kliman suggested that the etiology in Luke’s case may have been an immune response to his particular genetic makeup, citing a case of twins where one baby was immunologically attacked by the mother and the other was not. “The genetics of that particular fetus was expressing something that caused [the attack] to happen and the other one was not,” he said.

Although autoimmune disorders can be implicated in MPFD cases, Dr. Kliman said it’s unlikely I have one. When I asked about antiphospholipid antibody syndrome, which can be asymptomatic, manifesting only in pregnancy, he said it’s overdiagnosed.

Dr. Kliman was careful to express repeatedly that Luke’s death was not my fault. When I noted that Luke appeared to be of normal weight at his 32-week growth scan—suggesting to me that the condition had kicked in sometime after 32 weeks—he pointed to a recent study on how common it is for ultrasound technicians to overestimate fetal weight (resulting in pressure on mothers to deliver by C-section). “This was a process that I’m sure was happening from the very beginning of pregnancy,” he said.

Treatment for a subsequent pregnancy

We spoke at length about a treatment plan for a subsequent pregnancy. Because immunosuppressive therapy doesn’t work in cases of intervillositis, Dr. Kliman suggested starting with one baby aspirin per day from the beginning of pregnancy, to prevent clotting. I would start low molecular weight heparin, which can also prevent clotting, only if the same problem started to present itself, as there may actually be no issues in the next pregnancy, if in fact the immune attack in Luke’s case was a response to his particular genetic makeup. “If the placenta is normal size, there’s no indication in my opinion to do something that has some risk to you, and heparin is low risk but not zero risk,” Dr. Kliman said.

I’ll also be receiving more frequent ultrasounds in a subsequent pregnancy, for which Dr. Kliman wants to use the estimated placental volume technique he developed with his father. This simple set of measurements of the placenta’s width, height, and thickness can be compared to normative curves for placentas of the same gestational age. (Unfortunately, ultrasound technicians normally don’t measure the placenta or the umbilical cord; the standard of the care in the U.S. is to “follow the fetus” and the fetus only.)

“You did extra nothing in the second pregnancy and you made it to 37 weeks,” Dr. Kliman said. “That pregnancy would have survived if we would have known beforehand and we delivered you. So we can at least do that for you. But I think we can do a little better. We can at least have better growth and be aware of it. If we see nothing and there are no problems, then we just continue to follow you. If there’s another very small placenta, I would not go to 37 weeks.”

Dr. Kliman noted than in cases of renal failure, the kidneys can go all the way to a 90 percent loss of their units because the remaining 10 percent are operating at 500 percent efficiency. “This is how all organs that have many little units fail,” he said, likening the scenario to pregnancy. “The problem is this crash,” he said, as he drew a graph with a straight line that plummeted at the very end. “We want to see that we’re going down this pathway. If you’re only looking at this axis, which is the fetus, everything looks OK right until the very end. So we need to understand what’s happening here”with the placenta, pointing to the line before the crash.

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