The Aschheim-Zondek test, or A-Z test, the earliest version of the chemical pregnancy test, was refined in Scotland in the 1930s. This test involved injecting sexually immature mice, rabbits, and frogs with urine from potentially pregnant women, then examining the animals' uteruses after three days. A positive result indicated the presence of placental matter, identified by the hormone human chorionic gonadotropin (hCG). Over the decades, these tests evolved, leading to the first rapid at-home tests in the 1980s, all based on the same principle of detecting hCG.
Home pregnancy tests have indicated that I have been pregnant five times. I have used modern tests and seen numerous positive results. However, I did not initially grasp that these tests create a misleading binary of pregnant versus not pregnant. It is possible to be in a state of uncertainty regarding pregnancy and still receive a positive result.
hCG levels can rise due to chemical pregnancies, where genetic errors prevent the pregnancy from developing, or ectopic pregnancies, which typically do not result in a live birth. A positive test can occur if a miscarriage is imminent, if one is currently miscarrying, or if a pregnancy has ended but the body has not yet expelled the tissue. During my fourth pregnancy last year, I experienced this uncertainty; my home tests were positive, but my clinic's hCG measurements were low, leading doctors to warn of a probable miscarriage without a clear timeline.
Pregnancy tests, especially at-home urine tests, capture a specific moment when an embryo has implanted and is interacting with the uterus. However, these tests provide limited information, as they cannot quantitatively measure hCG levels over time or include ultrasound data necessary to assess a pregnancy's viability. Most pregnancies that implant in the uterine lining are not viable.
Before widespread chemical testing, pregnancy was less clearly defined. Many doctors and patients were hesitant to adopt the A-Z test, preferring to wait until after a missed period. Some doctors opposed home pregnancy tests due to their unreliability and a desire to maintain their authority.
Despite these concerns, home pregnancy testing has become a billion-dollar industry, and these kits have become culturally synonymous with pregnancy. The phenomenon of online pregnancy announcements reflects this, where reactions to a single test result are shared widely. However, this practice often occurs before the recommended twelve-week mark, when enough information to assess viability is typically available. Such announcements can obscure the reality that a single test cannot provide a complete picture of a pregnancy.
Biological anthropologist Kate Clancy discusses these themes in her book “Pregnancy Interrupted,” which examines the myths surrounding pregnancy and the oversimplification of the experience. Clancy highlights the complexity of pregnancy, noting that many pregnancies end without a live birth.
As I approach my due date, I reflect on my experiences with pregnancy. For much of this year, I was in a state of uncertainty, feeling pregnant but not fully convinced. The experience of being pregnant after multiple early losses alters one’s perception of time and certainty. With each passing day, the likelihood of a healthy delivery increases, yet new uncertainties arise.
Determining viability often relies on arbitrary guidelines. For instance, U.S. and U.K. definitions of miscarriage differ based on gestational sac sizes, leading to inconsistent diagnoses. Medical practitioners typically use gestational age, calculated from the first day of the last menstrual period, which can be inaccurate due to variations in menstrual cycles. This can lead to misinterpretation of healthy pregnancies as nonviable.
Clancy recounts a case where a patient received two fetal-age estimates that differed by four weeks. This discrepancy created confusion regarding the viability of the pregnancy when the patient began bleeding. Such variations highlight the significant margin of error in early pregnancy assessments.
The term intrauterine pregnancy of unknown viability (I.P.U.V.) is used to describe pregnancies that fall into a gray area between viable and nonviable. Clancy notes that this term can apply to various early pregnancy scenarios, and research indicates that a portion of I.P.U.V. cases can turn out to be viable.
The uncertainty associated with I.P.U.V. can heighten the emotional turmoil experienced during miscarriage, where individuals may struggle to balance hope and grief. This uncertainty is not limited to miscarriage; all pregnancies involve waiting for critical milestones, such as a heartbeat or test results.
Online pregnancy announcements can create the impression that discovering a pregnancy is a singular moment, overlooking the complexities involved. Confirming a pregnancy is more about ruling out possibilities than finding definitive answers. Clancy’s doctor aptly summarized this by stating, “Life is a movie, not a picture.”
Early miscarriages often occur as part of the natural process of discarding genetic errors. Chemical pregnancies may go unnoticed if individuals are not actively trying to conceive. These occurrences are common and reflect the complexities of human biology.
Understanding that pregnancy loss is frequent does not imply it should be dismissed as unpreventable. Pregnancy can be interrupted by biological factors, environmental influences, and societal factors, as well as personal choices.