In human females, the biology of reproduction is dangerous, messy, slow, often goes awry, sometimes produces less than perfect results, and doesn’t lend itself to rigid categorizations of “life versus not life.” All reproductive processes are a gradual continuum: Butterflies are not born overnight, frogs don’t arise instantaneously from frog eggs, and human embryology demonstrates that egg-sperm fertilization doesn’t produce instant babies; it produces a zygote.
Fetal or conceptual age is measured from conception, near the time of ovulation. Because most women are not aware when ovulation occurs, gestational age is measured from the first day of the previous menstrual period and includes the two weeks before conception. Gestational age is conventionally expressed in completed weeks. For example, a 22-week, 6-day fetus is considered a 22-week fetus. The first 13 weeks of gestational age constitute the first trimester. Weeks 14–27 make up the second trimester, and weeks 28–41 the third trimester. Fetal or conceptual age is two weeks shorter than gestational age. When current and future state laws refer to weeks of pregnancy, therefore, it is important to understand exactly what age is being cited. Does a ban after 6 weeks include the two weeks before conception or not? Lack of precision here will raise questions about pending and triggered legislation at the state level.
From Egg to Viability
If the egg, released from the ovary at day 13–15 of the menstrual cycle, meets a sperm in the Fallopian tube, that becomes day 1 of fetal age. If the egg does not meet a sperm, the egg is expelled through the uterus and the vagina. By days 3–5 of fetal age, cellular division has occurred and the 8–16 cell clump migrates through the Fallopian tube toward the uterus. By one week of fetal age (three weeks of gestation), the clump of cells (morula) has transformed into a hollow ball of cells called a blastocyst, which may or may not implant into the uterus. Implantation usually takes place 14 days after conception (4 weeks of gestation). A third to one-half of all fertilized eggs never fully implant and are expelled. Pregnancy is considered established only after implantation is complete. In some cases, the morula may not make it to the uterus but implants in the Fallopian tube, producing an ectopic pregnancy.
At gestational age 4 weeks (conceptual age 2 weeks), the zygote is the size of a pinhead. At that time the pregnancy test is likely to be positive. The embryonic stage lasts from 5 to 10 weeks of gestation. At 5 weeks of gestation, the embryo is the size of a pea. Many birth defects occur at this juncture in embryological development. By 8 weeks of gestation, the embryo is the size of a bean, and by 10 weeks of gestation, the embryo tail has disappeared and the embryo is now called a fetus.
Much has been made of the “fetal heartbeat” at 6 weeks of gestation. Strictly speaking, this is an “embryonic heartbeat,” as the embryo is not yet classified as a fetus. Many envision a fully formed heart, but that is not the case. At 6 weeks of gestation, ultrasound can pick up a flutter where the future heart will be; the ultrasound is detecting electrical signals from cells that will be the future heart’s pacemaker. If a stethoscope were applied to the mother’s abdomen, the “heartbeat” would not be audible this early. Much also has been made of “fetal pain.” Fetal pain is not possible before a minimum of 24 weeks of gestation because the neural circuitry required for the perception of pain is not yet developed.
Viability of the fetus—a fundamental, defining concept—is the capacity of the fetus for prolonged survival outside of the mother’s uterus. Modern neonatal technology has lowered the gestational age at which viability is possible. At the time of Roe v. Wade (1973), possible viability occurred at about 28 weeks of gestation, though many fetuses born at 28 weeks did not survive. Since Roe, the potential for viability has dropped to 23–24 weeks of gestation, now clearly limited further by profoundly immature lung development. In truth, babies born at 22–24 weeks are described as “peri-viable,” meaning that there is a chance, though not a likelihood, of survival. Only one in 10 such babies survives to go home, and that is after months of neonatal ICU care. These babies’ eyes are fused shut, their skin is gelatinous, and their lungs are so immature that they are not capable of anything resembling normal function. The majority of such babies that survive have profound intellectual impairment, cerebral palsy, blindness, deafness, seizures, impaired lung function, and a shortened life span that will necessitate multiple hospitalizations. Providing peri-viable care in the NICU is phenomenally challenging and discouraging, not to mention life altering for the infant’s parents, who will face heartbreak and stresses for which they are never fully prepared.
Nature Doesn’t Always Get It Right
Ectopic pregnancies occur in about 1–2 percent of known pregnancies. In an ectopic pregnancy, there is no way for the embryo to grow and develop properly. The growing embryo will rupture the wall of the Fallopian tube and the woman will bleed massively into the abdominal cavity. If the pregnancy is not aborted emergently, she will bleed to death.
Early pregnancy loss (miscarriage) occurs in about 10 percent of known pregnancies, usually within the first trimester. Incomplete miscarriage (failure of all the fetal contents to detach from the uterus) requires removal via aspiration or dilatation and curettage, or continued bleeding and infection will ensue. Miscarriages can be indistinguishable from an abortion and are often called spontaneous abortions.
Only 1.3 percent of abortions are performed at 21 weeks of gestation or later. Reasons for such abortions include catastrophic events such an abrupted placenta, infection and sepsis from premature rupture of membranes, severe life-threatening pre-eclampsia, and conditions of the fetus that are poorly compatible with survival outside the uterus, such as anencephaly or trisomy 18, are indications for abortion.
Abortion Is Health Care
Based on the science, biology, and medicine, abortion is a necessary tool in the armamentarium of quality obstetric and gynecological care. Banning abortion puts physicians in impossible positions. Their first obligation is to their patient (beneficence, non-maleficence). Current abortion bans during previable gestations threaten the ability of physicians to provide lifesaving care to women. No physician should have to choose between saving a patient and losing her or the license to practice medicine and possibly being jailed. No woman should face arrest for needing abortion services. Abortion as medical care is a decision between a patient and her physician, never to be taken lightly and too complex, nuanced, and important to be regulated with blunt religious, ideological, or legal instruments.
The viability standard that Justice Harry Blackmun articulated aligned with the biology of reproduction and allowed for patient autonomy and reasoned medical judgement. It should be retained. No woman ever approaches abortion frivolously. Abortion is and must remain health care.
—Margan Zajdowicz, MD, MPH
Full disclosure: I am not an ob/gyn physician. I am a board-certified pediatrician who has worked in a neonatal intensive care unit and cared for children who were graduates of the NICU.
