Chrissy Teigen and her husband, John Legend, suffered an experience too well known by many women: a pregnancy loss. Their response was a heartfelt show of grief on social media. While this gets significant attention due to the couple’s celebrity status, it brought to light that too often, the pain from a pregnancy loss is trivialized. Many will say that early losses are common (yes they are) and that most women can successfully achieve a subsequent pregnancy. Yet, this doesn’t render the pain any less difficult. Ms. Teigen shared that sense of loss with all of us.
While the gestational age of their pregnancy was not known, she did share that she was at the halfway point, which would make it about 20 to 24 weeks. Pregnancy loss at that gestational age occurs in one in 150 pregnancies. Pregnancy loss when the pregnancy is less than 12 weeks occurs between 10 to 15 percent of the time. But human reproduction is highly inefficient since women create six to seven million eggs (oocytes), potentially ovulate 400 and average nine to 10 pregnancies in societies where contraception is not practiced.
Understanding Pregnancy Loss
So, after the grief, the loss and the tears, the question remains: “Why is human reproduction so inefficient?” One hypothesis is that the inefficiency provides the human species with a way to adapt to many different environments and thus has been responsible for allowing humans to exist as a species.
Homo sapiens is the only survivor from the genus homo. There were numerous ancestor genus and species – what happened to the Neanderthals or the Erectus? One theory posits that Sapiens survived because the members of the species went into a wide range of habitats and survived there. Sapiens survived because they were highly adaptive. Certain physical features gave Sapiens some advantage. For example, while many animals, especially primates have a prehensile thumb, human thumbs extend farther across the hand to allow for finer grasping abilities. The ability to walk evolved from ancestors over four million years ago. Humans developed the ability to use tools. They developed large and complex brains and a complex language. Humans evolved a sense of time and repetitive occurrences which allows them to synthesize solutions to new data based upon past experience. Thus, as humans evolved and ranged in many different environments, they survived.
Some of which can be attributed their mating with other Hominids and succeeding by assimilation. Neanderthals and humans inhabited many of the same areas, but humans prevailed. Partly because they did mate, but humans also have extra genes that are associated with aggressive behavior. And so, in the end, one way by which humans adapted was through genetic diversity. Perhaps they became more aggressive and this may have been one reason why Neanderthals were less competitive. However, genetic diversity played a large role in the emergence of homo sapiens.
Genetic diversity and plasticity are at the core of sustainable life. Evolution modifies the genetic constitution of an organism to provide a succession best adapted to a particular environment. Superimposed on this is a system for modifying the genetic messaging allowing adaptability to the unique, and perhaps not recurring environment. Adaptability relies upon a genetic system that is plastic and fluid, balancing a need for consistency with a need to change.
Humans survived because of their adaptability. What is the price of that adaptability? Reproductive “waste” is the price for the success of homo sapiens. Clinically, one manifestation of that price is recurrent pregnancy loss. Thus, in order to speciate, there needs to be genetic stability and to adapt, there needs to be genetic instability. When the genetic instability creates a clinical condition that does not produce normal children, then survival stops and pathology prevails.
If all things were ideal, they wouldn’t be perfect.
If human reproduction was highly efficient then a woman would develop one oocyte (egg), she would ovulate, have intercourse, conceive and deliver a child. Nothing could be farther from the truth. So, if you were nature, you could meet the need for adaptability by starting with a very large number of oocytes so that at least some of the eggs could meet almost any condition and result in the birth of a child. But having a child is a heavy burden on women and families overall, regardless of their desires. So, if a lot of the eggs are not going to make a child, it is necessary to eliminate them at an early stage which lessens this burden. As mentioned, most of the potential pregnancies are lost as oocytes move from stored eggs to ovulated eggs.
Once an egg is ovulated, why is there still considerable pregnancy loss? A major reason for the loss of embryos as they move into the uterus, implant and grow to the point of being visible on ultrasound, is that the need for genetic plasticity causes most human embryos to have the wrong number of chromosomes (aneuploidy). Most pregnancies with an abnormal number of chromosomes will not develop to term but rather result in undetected loss or miscarriages. The early loss reduces further the burden on women since to carry a pregnancy to term requires considerable resources the farther into the pregnancy she progresses.
Since Ms. Teigen’s pregnancy seems to be have occurred in the second trimester, pathology in the genetic makeup is less frequent. This only increases the pain, because the loss is one of an apparently normal child. Hopefully, Ms. Teigen and Mr. Legend can ignore the uncaring comments on social media and realize that anyone who has lost a pregnancy, at any stage, will empathize completely with them and understand their pain. For those who have used IVF, the sense of loss can come as early as receiving a call from an embryologist that their embryos did not survive to the point where they could be transferred.
A loss of any type need only be measured by the one experiencing it. Despite understanding the evolutionary and even medical reasons, first we must realize the need to feel and heal – before moving on.
This article was written by Dr. John Rinehart and originally posted on 30seconds.comLeave a reply