Between 1991 and 1994, Christian Peeters and Bert Hölldobler studied the reproductive behaviors of the Indian jumping ant (Harpegnathos saltator), a species native to southern India. They conducted experiments as part of a larger investigation into conflict and reproductive behavior among ants. Peeters and Hölldobler discovered that Indian jumping ant colonies contained both sexually reproductive workers and egg-laying queens. In most other species of ant, the queens are the only sexually reproductive individuals. After conducting their experiments, Peeters and Hölldobler argued that queens and sexually reproductive workers cooperated in the Indian jumping ant species to establish and preserve new colonies.

In the 1950s and 1960s, researchers Leon Chesley, John Annitto, and Robert Cosgrove investigated the possible familial factor for the conditions of preeclampsia and eclampsia in pregnant women. Preeclampsia and eclampsia, which are related to high blood pressure, have unknown causes and affect at least five percent of all pregnancies. The researchers, who worked at Margaret Hague Maternity Hospital in Jersey City, New Jersey, used hospital patient records to find and reexamine women who had eclampsia at the hospital, as well as their daughters, sisters, daughters-in-law, and granddaughters. Chesley and colleagues found that the daughters and granddaughters of eclamptic women were more likely than the female offspring of non-eclamptic women to have preeclampsia and eclampsia in their own pregnancies, and especially in their first pregnancies. The study provided evidence that the disorders are inherited, enabling physicians to better monitor pregnancies in women who have a known family history for preeclampsia and eclampsia.

The book Infant Mortality: Results of a Field Study in Johnstown, PA., Based on Births in One Calendar Year (1915), written by Emma Duke, detailed one of the first infant mortality field studies conducted by the US Children's Bureau. In the study, Duke and her colleagues collected information about over one thousand infants in the city of Johnstown, Pennsylvania. They used that information, along with interviews conducted with the families of the infants, to identify factors that affected infant mortality rates in the community. Duke and her team found strong correlations between elevated infant mortality rates and conditions experienced by Johnstown residents of lower socioeconomic status. The design and implementation of the study described in Infant Mortality: Johnstown, PA provided a model for future Children's Bureau research that resulted in seven additional infant mortality studies in other US cities. Infant Mortality: Results of a Field Study in Johnstown, PA., Based on Births in One Calendar Year quantitatively demonstrated the link between poverty and infant mortality.

In the early 1920s, researchers Edgar Allen and Edward Adelbert Doisy conducted an experiment that demonstrated that ovarian follicles, which produce eggs in mammals, also contain and produce what they called the primary ovarian hormone, later renamed estrogen. In their experiment, Doisy and Allen extracted estrogen from the ovarian follicles of hogs and proved that they had isolated estrogen by using a measurement later renamed the Allen-Doisy test. Allen and Doisy’s 1923 experiment to isolate estrogen showed it was made within the ovaries and also established a method for isolating the sex hormone. That method provided a basis for future research on hormones. Later researchers showed that estrogen functions in the menstrual cycles of primates by signaling for the tissue lining the uterus (endometrium) to thicken in preparation for possible implantation of a fertilized egg.

In 1968, pediatric researchers Jerold Lucey, Mario Ferreiro, and Jean Hewitt conducted an experimental trial that determined that exposure to light effectively treated jaundice in premature infants. The three researchers published their results in 'Prevention of Hyperbilirubinemia of Prematurity by Phototherapy' that same year in Pediatrics. Jaundice is the yellowing of the skin and eyes due to the failure of the liver to break down excess bilirubin in the blood, a condition called hyperbilirubinemia. Bilirubin is a product that results from the degradation of red blood cells, which the immature liver of premature infants often has difficulty breaking down. Lucey's group's study demonstrated both the efficacy of phototherapy, which uses light to breakdown the bilirubin in the blood, as treatment for hyperbilirubinemia. As a result of Lucey's research team's study, physicians adopted phototherapy as the standard of care for treating premature infants born with jaundice.

In 1980, Ernesto Ippolito and Ignacio Ponseti published their results on a histological study they performed on congenital club foot in human fetuses. The researchers examined the feet of four aborted fetuses and compared the skeletal tissues from healthy feet to those affected by congenital club foot. Infants born with club foot are born with one or both feet rigidly twisted inwards and upwards, making typical movement painful and challenging. Ippolito and Ponseti studied how the connective tissues, such as the ligaments and tendons stretching across the foot and ankle, function to pull the affected foot out of place as the fetus develops. Their findings helped researchers determine club foot’s potential causes and possible treatments by focusing on connective tissues.

In the early twentieth century US, Jean Paul Pratt and Edgar Allen conducted clinical experiments on women who had abnormal menstrual cycles. During the clinical tests, researchers injected the hormone estrogen into their patients to alleviate their menstrual ailments, which ranged from irregular cycles to natural menopause. The hormone estrogen plays a prominent role in the menstrual cycle by signaling the tissue lining the uterus (endometrium) to thicken in preparation for possible pregnancy. In their clinical tests, Pratt and Allen showed that injecting estrogen into female human subjects restored their normal menstrual cycle, removed symptoms such as hot flashes, and caused uterine tissue to grow. The clinical tests conducted by Pratt and Allen provided experimental evidence and justification for the injection of isolated estrogen in women to alleviate, for a short amount of time, different menstrual problems, and it contributed to later hormone therapy research.

Jeffrey Weinzweig and his team, in the US at the turn of the twenty-first century, performed a series of experiments on fetal goats to study the feasibility of repairing cleft palates on organisms still in the womb. Weinzweig , a plastic surgeon who specialized in cleft palate repair, and his team developed a method to cause cleft palates in fetal goats that are similar to clefts that occur in human fetuses. Using their goat congenital model, the team developed a method to repair a congenital cleft palate in utero, or in the womb. The resultant goat newborns had fully developed palates without scarring and with minimal functional impairment. The researchers recommended that surgeons use their repair methods in humans to decrease the incidence of speech impairment commonly associated with cleft palate patients.

In 2004, Shu-Shya Heh, Lindsey Coombes, and Helen Bartlett studied the association between Chinese postpartum (post-childbirth) practices and postpartum depression in Taiwanese women. The researchers surveyed Taiwanese women about the social support they received after giving birth and then evaluated the depression rates in the same women. Heh and her colleagues focused on the month following childbirth, which according to traditional Chinese medicine, is an important period that warrants a set of specialized practices to aid the woman's recovery. Collectively called zuoyuezi (doing the month), the postpartum practices require the help of someone else, typically the woman's mother or mother-in-law, to complete. Heh and her colleagues found that generally, Taiwanese women with more social support displayed fewer postpartum depressive symptoms, and concluded that the practice of doing the month helped prevent postpartum depression in Taiwanese women.

In the early 2000s, Sabata Martino and a team of researchers in Italy and Germany showed that they could reduce the symptoms of Tay-Sachs in afflicted mice by injecting them with a virus that infected their cells with a gene they lacked. Tay-Sachs disease is a fatal degenerative disorder that occurs in infants and causes rapid motor and mental impairment, leading to death at the ages of three to five. In gene therapy, researchers insert normal genes into cells that have missing or defective genes in order to correct genetic disorders. The team created a virus that coded for a specific gene missing in mice with Tay-Sachs. That missing gene is called hexosaminidase subunit alpha (HEXA). Martino and the team injected the virus into the brains of mice with Tay-Sachs in attempt to restore Hexa enzymatic function in the brain and spinal cord (central nervous system).