Thin Blue Line: A History of the Pregnancy Test

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"Am I pregnant?"The answer to this age-old question once demanded a combination of guesswork, intuition, and time. In 1978, however, the long wait to know for sure became a thing of the past. Trumpeted by advertisements as “a private little revolution,” the first home pregnancy tests started appearing on drug store shelves that year. Nearly half a century later, innovations promise to make even the telltale thin blue line obsolete.The home pregnancy test works by identifying the presence of the “pregnancy hormone,” human chorionic gonadotropin (hCG), in urine. Research that led to a sensitive, accurate test for hCG was done by scientists in the Reproductive Research Branch of the National Institute of Child Health and Human Development at NIH.For young researchers interested in reproductive hormone studies (reproductive endocrinology) in the late 1960s, the National Institutes of Health (NIH) was an ideal location. Two key researchers came to the NIH in 1970 specifically to do research in this field. Judith Vaitukaitis and Glenn Braunstein, both medical residents in Boston (at different hospitals) in 1969, talked to their colleagues about where to pursue hormone research. Each heard the same message: go to Bethesda and talk to scientists Mortimer Lipsett and Griff Ross. Vaitukaitis arrived at NIH on a special postdoctoral fellowship and would become one of the first female senior investigators in her Institute. For Braunstein, NIH provided an opportunity to fulfill his military duty by signing up with the Public Health Service instead of going to Vietnam, and he came as a Clinical Associate.Judith Vaitukaitis (JV): I came to [NIH to] stay for six weeks or six months, and I stayed almost six years. It was probably the most fun time of my life. It was the kind of scenario that, if I were independently wealthy, I would have done it for nothing.JV: I think I may have been the first woman senior investigator [at NICHD]. But I was so used to it. In med school there were five or six women [in my class]. I can remember one of the guys walking up to me and saying, “You know, if you weren’t in this class, I’d be rated higher.” And I said, “Tough! Why don’t you work harder?” I’ll never forget that.Glenn Braunstein (GB): I applied to go to the NIH to work with Griff Ross, but did not hear until the day before I was to sign my commission papers for the Army. The telegram said that I would be commissioned in the Public Health Service. This gave me the opportunity to fulfill my military obligation while working at the one place then on the cutting edge of hCG research.Both young doctors arrived in Bethesda in 1970 and in the years they spent with the Reproductive Research Branch—first at the National Cancer Institute (NCI) and then at the National Institute for Child Health and Human Development (NICHD)—they found an active community for the study of reproductive endocrinology. Because of the newness of the field, they could practically publish a paper from every result.JV: [NIH] was one of the few places in the country where one could do reproductive endocrinology. It was a new field. And the thing was that no matter what we did, it was brand new, so everything was publishable.JV: It was Building 10, 10B09. It was in a small laboratory, and for periods of months, there would be about 10 of us working in that space. I used to get over there about six o’clock in the morning and not leave till eleven o’clock at night. There were quite a few that worked long hours. The second or third year I was here, I think I published 28 papers in one year. They weren’t piddling kinds of things. I mean, there were so many things that one could do if you decided to think it through to understand what in the world’s going on. It was the way research should be.Human Chorionic Gonadotropin (hCG) was a fascinating hormone to study in 1970, partly because not much was known about its behavior or makeup. Scientists did know that the human body secretes hCG only during pregnancy or during certain kinds of cancers. If they could find a way to precisely measure the hormone, they would have a reliable tumor marker, as well as a way to identify problems with a pregnancy. NCI’s Roy Hertz was studying a cancer called choriocarcinoma at the time. In this disease, patients exhibited tumors that secreted hCG. The clinicians wanted a way to test blood samples reliably for the presence of hCG so that they could track the tumor during treatment.JV: We knew that the bioassay that was used for monitoring the amount of hormone they were measuring was very crude, very insensitive, but it was better than anything else we had at that time. So we needed another way of measuring the hCG in the presence of a finite amount of LH [luteinizing hormone].JV: While we were doing this, we had no idea of the impact on early pregnancy detection, abnormal pregnancy detection. In ectopic pregnancy, the levels of hCG usually start falling and they don’t rise as high as they do within a normal pregnancy.However, measuring precise levels of hCG is exactly what the bioassays of the mid-twentieth century and the immunoassays of the 1960s could not do. The best test they had in 1970 was an immunoassay that could measure hCG but could not distinguish between hCG and luteinizing hormone (LH), another of the human gonadotropins that shares its biological characteristics.GB: Griff and I spoke. “Wouldn’t it be great to develop a new assay for hCG.” At that time Judy Vaitukaitis was immunizing rabbits with subunits of hCG and harvesting antibodies.Vaitukaitis was working at separating the subunits of hCG and determining their biological function and characteristics. In 1970 and 1971 she worked on generating an antibody that would be specific to the beta-subunit of hCG and that could therefore be used in a radioimmunoassay—so called because the process used radioactive labels in the immunoassay—and would not cross-react with other hormones in the body. In 1972, she found it. The first rabbit to produce the antibody was called “SB6” and became the baseline for future experiments.JV: We were looking at structure-function studies of human chorionic gonadotropin. Was there biologic activity in the isolated subunit? What was it about the molecule that was responsible for the unique immunologic and biologic activity? Then we realized that the biologic effect of the hormone resided in the beta unit of hCG. So in doing these structure-function studies to understand where the immunologic and biologic specificity resided, it became obvious that you could really take advantage of the relative specificity of the antiserum.JV: It was critical for [NICHD’s] John Robbins to be involved with this because he had the immunology background. Actually, we tried two doses of immunogen [to make the antibody], 10 and 50 micrograms, and so the animal that had the first dose of 50 micrograms of immunogen was labeled SB6, since it was the sixth rabbit. There were five rabbits immunized with 10 micrograms, and we were told they would never make antibody at 10. I said, “Let’s see.” We went down subsequently to 2 and showed it would respond at that, too. So the first animal that was immunized with 50 micrograms, SB6, became the classic antiserum that had the best relative specificity that was used for years, and we provided it all over the place.At NIH, scientists at intramural institutes in Bethesda have the opportunity both to work at the laboratory bench and follow patients at the Clinical Center. Though the Reproductive Research Branch had moved to NICHD, the scientists collaborated with cancer researchers at NCI. Vaitukaitis and her colleagues examined patients with choriocarcinoma, a type of cancer in which patients showed elevated levels of hCG. While simultaneously working on purifying and developing tests for identifying hCG in human serum, they could study both current Clinical Center patients and blood samples previously collected by the NCI and frozen for research.JV: In screening some of these patients, we routinely took blood and measured hCG in them. We started turning up hCG levels in some of these patients. This was brand-new territory. But here we were working in a laboratory—it really underscores why you need physicians to be involved with clinical research. If you can make the diagnosis, you had a way of treating the disease.GB: So we went to the freezer. Griff Ross had serial samples from women with choriocarcinoma and we put those samples into the assay. Some of the women who were supposed to be cured actually still had hCG. We started to look at other types of cancers, too. Tom Waldmann at NCI also had a freezer full of blood samples from cancer patients, both single and serial samples. We put the samples through the assay, and found that 18% of the nontrophoblastic tumors showed levels of hCG. This was news: hCG was a tumor marker for non-trophoblastic tumors as well as trophoblastic tumors.Research at NIH, as elsewhere, is a collaborative experience. Griff Ross’ group needed some basic research tools to do their studies, including, among other things, purified hormone and urine from post-menopausal women. These substances would be used for experiments as the scientists learned more about hormones and the human body. The group used hCG purified by NICHD grantee Robert Canfield, known as the CR preparation of hCG, for “Canfield-Ross.” For other research supplies, they turned to some unusual sources.JV: Canfield’s laboratory was isolating the human chorionic gonadotropin from the pregnancy urine, and he had isolated it and broken it down to two subunits. That was back in the days where you had to do things by hand, and so the throughput was very slow and tedious.JV: We were doing studies on follicle-stimulating hormone [FSH]. It was like hCG but it has a different biologic effect. We wanted to study the biologic effect of FSH, so we contacted a retirement home for nuns and arranged with the nuns to collect their urine and put it in these big plastic containers. [We would] go over there once a month with somebody who was strong enough to lift these bottles. I would say probably each plastic container held probably about 15 gallons of urine. We would take it back and then process it to isolate the FSH from it, [and] then use that to study what the effect of sialic acid was on hormone action. It was unbelievable, but we got a lot of stuff done with that. I would never want to do it again!In 1972, Vaitukaitis, Braunstein, and Ross were ready to publish their major paper on hCG research, in which they described their methodology for using antibodies to the beta subunit of hCG in a radioimmunoassay to identify and measure hCG in the presence of LH. Before publishing, they met with the NIH lawyers to discuss patenting their process. Surely none in the room that day could have predicted the multi-million dollar business that the home pregnancy test would become within the next few decades. However, the test’s usefulness as an accurate tumor marker alone might have justified the patent, since by then the team had already used the test on Clinical Center patients and proved its reliability. But NIH declined to patent the test. Since the work was done using public funds, went the argument, the results should go immediately into the public domain, with no royalties for either the government or the scientists. This policy has since been changed. NIH now submits patents listing the scientists as co-inventors, and the scientists can receive limited royalties from their discoveries. But the millionaire’s life was not to be for the NICHD researchers.JV: One of our concerns was that we [had] developed this assay and we wanted to protect the public from getting gouged with being charged for these tests, because we knew it would be picked up by the commercial outfits. But the legal counsel [of NIH] would not at that time allow patenting.GB: We knew this would be a fantastic pregnancy test. We went to the government lawyers and said, “This is a technique that is going to be extraordinarily useful. Why not have NIH profit from it?” But since it was developed with public funds, the lawyers said no.In the 1970s, the researchers went on to other subjects. Vaitukaitis returned to Boston to spend a decade at the Boston University School of Medicine before returning to the NIH in 1986 to work with the division that would become the National Center for Research Resources (NCRR). She has served as Director of NCRR since 1993. Glenn Braunstein went to California, where he continues research on hCG and other reproductive hormones at Cedar-Sinai Medical Institute in Los Angeles. In his long and illustrious career at NIH, Griff Ross would attain the posts of chief of the Endocrinology and Reproduction Research Branch, clinical director of NICHD, scientific director of NICHD, and associate director of the Clinical Center.In 2003, as NICHD celebrated its fortieth anniversary, Institute Director Dr. Duane Alexander singled out the pregnancy test research as some of the most seminal work done by the Institute over its four decades. Judith Vaitukaitis was inducted into the NICHD Hall of Honor “for discovery of the beta subunit of human chorionic gonadotropin and identifying it as the earliest marker of pregnancy, leading to its development as the standard pregnancy test and as a monitor for response to cancer treatment.”Note: Quotations labeled “JV” are from an interview with Judith Vaitukaitis, August 18, 2003. Quotations labeled “GB” are from a telephone conversation with Glenn Braunstein, October 3, 2003.1350 BCEOne of the earliest written records of a urine-based pregnancy test can be found in an ancient Egyptian document. A papyrus described a test in which a woman who might be pregnant could urinate on wheat and barley seeds over the course of several days: “If the barley grows, it means a male child. If the wheat grows, it means a female child. If both do not grow, she will not bear at all.” Testing of this theory in 1963 found that 70 percent of the time, the urine of pregnant women did promote growth, while the urine of non-pregnant women and men did not. Scholars have identified this as perhaps the first test to detect a unique substance in the urine of pregnant women, and have speculated that elevated levels of estrogens in pregnant women’s urine may have been the key to its success.Middle Ages through the 1600sUsing visual aspects of urine to detect pregnancy became a popular method. In Europe, so-called “piss prophets” claimed to be able to diagnose many different conditions and diseases by the color of urine. In a 1552 text, pregnancy urine was described as: “clear pale lemon color leaning toward off-white, having a cloud on its surface.” Other tests included mixing wine with urine and observing the results. Indeed, alcohol reacts with certain proteins in urine, so this may have had a moderate success rate.1800sVarious theories abounded, such as the possibility that pregnancy urine contained certain identifiable crystals or bacteria. Scientists did not know enough about pregnancy to develop a reliable test. However, for sexually active women, the best method for diagnosing pregnancy remained careful observation of their own physical signs and symptoms (such as morning sickness).1890sMany physicians began to describe the workings of chemicals in the body, suggesting that “internal secretions” by certain organs were crucial to an understanding of human biology. Ernest Starling named these chemical messengers “hormones.”American public health advocates started to encourage women to see their doctors as soon as possible after pregnancy was suspected. Prenatal care was found to improve the health of both infants and mothers, even though most women would not see a doctor or midwife until well into the pregnancy.1903Research on human reproduction intensified in the early twentieth century. Ludwig Fraenkel described the corpus luteum, the glandular mass that forms in women’s bodies during the normal menstrual cycle that we now know is supported by hCG during pregnancy. He identified some hormones that had a role in female reproduction, naming the hormone that promoted gestation, progesterone. Progesterone was isolated (an important step in the study of hormones) in 1934.1920sIndependently, scientists in several laboratories across Europe described the presence of a substance that promotes ovary development and growth in rabbits and mice. In Germany, Selmar Aschheim and Bernhard Zondek noted that this substance specifically affected the formation of the corpus luteum.Scientists recognized that there is a specific hormone (now known as human chorionic gonadotropin (hCG)) that is only found in pregnant women.1927Aschheim and Zondek described a test (known as the A-Z test) which identified the presence of hCG in urine. To test for pregnancy, a woman’s urine was injected into an immature rat or mouse. If the subject was not pregnant, there would be no reaction. In the case of pregnancy, the rat would show an estrous reaction (be in heat) despite its immaturity. This test implied that during pregnancy there was an increased production of the hormone. During early studies of the A-Z test, the scientists discovered that testicular tumors could produce hCG as well.1930sHormone research blossomed in this period. Scientists in several different laboratories developed bioassays (special tests using animals or live tissue) to identify hCG by injecting samples to induce ovulation in rabbits, frogs, toads, and rats. These tests were expensive, required the sacrifice of several animals, and slow, often taking days to get results. The tests were also insensitive when measuring hormone levels to diagnose pregnancy because of the similarity between hCG and another substance, luteinizing hormone (LH). Most bioassays were in fact unable to distinguish between the two except at extraordinarily high rates of hCG.Herbert Evans discovered that when injected with certain fluids from the female glands a female rat would grow an abnormally large corpus luteum. These fluids were hormones now known as gonadotropins.In the next few decades laboratory scientists increased their level of interest in the study of human reproduction and on the role of ovaries and testes in human development.1932The First International Conference of Standardization of Sex Hormones was held in London, marking the culmination of a decade of increased interest in the chemical properties of sex hormones rather than the previously limited focus on biological function.1930s-1940sPopular childbirth books began to encourage women to visit a doctor’s office for confirmation of pregnancy rather than relying on “old wives’ tales” for the diagnosis.1958Gonadotropins were first extracted from human pituitary glands.1960A “hemagglutination inhibition test” for pregnancy was developed by L. Wide and C.A. Gemzell. Because it used cells in the testing process, this test was an immunoassay rather than a bioassay. The test used purified hCG, mixed with a urine sample and antibodies directed against hCG. In a positive pregnancy test, the red cells clumped, displaying a particular pattern. This test was much faster and cheaper than the old bioassay, but still relatively insensitive, especially for early diagnosis of pregnancy. The test also cross-reacted with various medications.JV: The problem with these kinds of tests is that there can be some substances in the urine to give a false-negative or a false-positive test at a pretty high frequency, so you had to be careful. It was important to identify what were the interfering substances that gave false results.Mid-1960sImportant disease research in this period led to more knowledge about how hormones, steroids, and antibodies work in the human body. In the next decade, NICHD scientists would transfer these principles to their studies of reproductive hormones such as hCG.JV: The first principle of developing a radioimmunoassay was the result of a person making the observation that, when patients with diabetes mellitus were treated with insulin, they developed a circulating antibody. Then after that, we started inducing antibody in animal models, and the rest is history.JV: There were very few places that were doing reproductive endocrinology research [in the late 1960s and early 1970s] because they didn’t have purified hormones, and there were just some very tedious ways of doing things. To compare the research tools we had back in the late 1970s to now, it’s like Neanderthal to modern man. [There is] no comparison. It took brute force to get some things done.1966A. R. Midgley described the first radioimmunoassay for hCG, but the test still could not differentiate between hCG and luteinizing hormone. Several other laboratories reported improvements on this test, but did not solve this basic problem.1970sTwo things came together in this period along with the so-called sexual revolution: increased research on reproductive health and a heightened desire (brought on by both improved prenatal care and legal abortion) to detect pregnancy as early as possible. Beginning in the 1970s, prenatal care and prenatal testing became more routine in the American health care system.1970Tests available to doctors and technicians included Wampole’s two-hour pregnancy test. The test could be done as early as four days after a missed period. In the packaging materials, the man pictured performing the test wore a laboratory coat, indicating that it was not intended for home use. Besides the equipment in the kit, (two test tubes, a plastic rack, a bottle of “control solution,” a bottle of “hCG-antiserum” and a bottle of “cell suspension”), testers would need a small funnel and filter paper or centrifuge, clean pipettes or syringes, and saline solution in addition to a urine sample.1970-1972Scientists at NIH learned more about the properties of hCG. They were specifically interested in which parts of the hormone showed biologic activity. Using various methods, they identified two subunits of hCG and focused on the beta-subunit. They found that the beta-subunit is where the immunologic and biologic specificity of hCG resides (what makes it different from other hormones). Using animal models, they took advantage of this discovery to develop a specific antiserum for measuring the hormone in humans.In a 1972 textbook on gonadotropins, Vaitukaitis and Ross noted that: “Common antigenic determinants [biological characteristics] among hCG, LH, FSH, and TSH have made the production of specific antisera for radioimmunoassay difficult.” However, the team was close: “the recent isolation and separation of subunits… have provided unique materials with which these questions could be explored.”1972Vaitukaitis, Braunstein, and Ross published their paper describing the hCG beta-subunit radioimmunoassay that could finally distinguish between hCG and LH, therefore making it potentially useful as an early test for pregnancy. See Vaitukaitis, J.L., Braunstein, G.D., and Ross, G.T. (1972) “A radioimmunoassay which specifically measures human chorionic gonadotropin in the presence of human luteinizing hormone.” American Journal of Obstetrics and Gynecology, 113, 751-8.1973The first edition of Our Bodies, Ourselves, the women’s health manual written by the Boston Women’s Health Collective, noted that available pregnancy tests were most accurate if done two weeks after the missed period. Though the authors insisted that instructions for “collecting and submitting your urine are simple,” modern readers might disagree. “Drink no liquids after dinner the night before,” the text instructed, “then as soon as you awake in the morning collect a urine sample in a clean, dry, soap-free jar and take it to a laboratory.” Another possibility was sending the urine sample to a laboratory in North Carolina, after first writing to request the test kit.Mid-1970sThough the test was not yet widely available, NIH scientists spread the word about the new radioimmunoassay. At first, the test was found most useful for clinicians in testing and following patients being treated for hCG-secreting tumors. The sensitive radioimmunoassay could tell the doctors if the chemotherapy treatments had worked.
JV: We were doing assays for people all over the place. We felt ethically that we had to because it wasn’t available anyplace else. So we used to give out a lot of antiserums to research labs and show them how to set up the assays.1976FDA approval was sought by Warner-Chilcott for e.p.t, the “Early Pregnancy Test” later known as the “Error Proof Test.” e.p.t would become the first home pregnancy test kit on the market in the United States. The makers of e.p.t worked with the FDA to meet all the requirements of the 1976 Medical Devices Act. (The new regulations divided medical devices into three classes depending on potential for harm and misuse.) Approval was also granted to three other tests that were deemed “Substantially equivalent:” Predictor, ACU-TEST, and Answer.1976Several articles in the American Journal of Public Health stated that public health would be better served if the average consumer could purchase a home pregnancy test and use it reliably in her own home.1977By the end of 1977, e.p.t was ready for the American market. (Because of requirements for the specific wording on packaging and other last-minute details, there is a lag time between FDA approval and wide availability of most medical devices.) In a “Dear Pharmacist” letter from Warner/Chilcott, drug stores were informed that “the e.p.t consumer advertising campaign has been designed to direct the consumer to their drug store to purchase e.p.t”1978e.p.t was advertised in major women’s magazines including: Mademoiselle, McCall’s, Redbook, Family Circle, Ladies’ Home Journal, Good Housekeeping, and Vogue. Advertisements appeared later in the year for Predictor, Answer, and ACU-TEST.The e.p.t test of 1978 was described to the public in Mademoiselle: “For your $10,” the article notes, “you get pre-measured ingredients consisting of a vial of purified water, a test tube containing, among other things, sheep red blood cells…as well as a medicine dropper and clear plastic support for the test tube, with an angled mirror at the bottom.” The test took two hours, and was more accurate for positive results (97%) than for negative (80%). Advantages, noted Mademoiselle, included “privacy and not having to wait several more weeks for a doctor’s confirmation, which gives you a chance, if pregnant, to start taking care of yourself…or to consider the possibility of early abortion.” (Mademoiselle, April 1978, p. 86)McCall’s magazine claimed that “physicians we interviewed about the tests endorse the concept.” But the editors cautioned that women who get negative results and who still suspect pregnancy should not wait ten days to take the test again “but should seek medical help as soon as possible.” (McCall’s, March 1978, p. 46)1979Taking the test at home, noted a 1979 article in Family Planning Perspectives, both protected the privacy of a woman who might not want her doctor to know she is sexually active and gave women a new opportunity to take an active role in their own health care.1980sResearch increased and educational campaigns were launched to identify the importance of folic acid in early pregnancy and to warn of the dangers of various environmental hazards and alcohol to a developing fetus.1990sAdvances in the technology of pregnancy tests included the development of new types of antibodies and the use of enzyme labels in place of radioactive labels.2003The next generation of home pregnancy tests was ushered in with FDA approval of Clearblue Easy’s digital pregnancy test. In place of a thin blue line, the indicator screen will now display either “pregnant” or “not pregnant.”JV: The home pregnancy test is probably the most widely used test besides the hematocrit and hemoglobin [the blood test to measure red blood cells and iron levels that is part of the blood workup done regularly at doctors’ offices].
Advertisements for home pregnancy tests appeared in most American women’s magazines beginning in 1978. Seemingly aimed at white, middle class women, both married and unmarried, the advertisements appeared in the fashionable Vogue and Mademoiselle alongside articles about movie stars and advertisements for birth control, and in McCall’s and Ladies’ Home Journal amidst recipes and advertisements for baby food. At the cost of $10.00 the test kit was affordable for many, certainly, but not cheap. Today, most tests come in sets of two for well under twenty dollars.The emphasis in the early advertisements wavered between an emphasis on science and a more emotional appeal. The first e.p.t advertisement, for example, featured eight paragraphs of text, a diagram showing the use of the dropper and test tube, and a photograph of the kit itself, showing test tubes suspended in a plastic container. Conversely, the ACU-TEST advertisement from the same year showed a woman’s face under the phrase “I wonder if I’m pregnant.” Biting her fingernail and looking pensively off camera, the woman embodied the ambivalence that often accompanied this new technology.In many ways, a pregnancy test is difficult to market. The term “hCG” sounds foreign and the phrase “urine stream” is difficult to sugar coat. The test is so intimate that most advertisements focus on its accuracy or the short time frame to know the answer rather than on the meaning of the results. In the history of healthcare tests, the pregnancy test is unique in that—unlike blood tests for most diseases—a negative result can be cause for celebration for some, despair for others. With a pregnancy test, the reaction to the results is complex and depends on many personal factors.Whether a woman wants to be pregnant or not, she can now find out whether she is with startling accuracy, ease, and speed unimaginable to previous generations. Though her mother may not even have taken a pregnancy test, today, a woman can find out if she is pregnant four days before a missed period. A private little revolution, indeed.Alhough in early 1978 e.p.t had used words like “at last” and “finally” to introduce its new test, by the end of the year, this test had competition. In 1979 the advertisements started claiming that the test had been “introduced in May, 1976.” This was most likely a reference to when the test was approved by the FDA and tested by women as part of that approval process.