By 2011, researchers in the US had established that non-invasive blood tests can accurately determine the gender of a human fetus as early as seven weeks after fertilization. Experts predicted that this ability may encourage the use of prenatal sex screening tests by women interested to know the gender of their fetuses. As more people begin to use non-invasive blood tests that accurately determine the sex of the fetus at 7 weeks, many ethical questions pertaining to regulation, the consequences of gender-imbalanced societies, and altered meanings of the parent-child relationship.

In 2004, a team of researchers at Tufts-New England
Medical Center in Boston, Massachusetts, investigated the fetal
cells that remained in the maternal blood stream after pregnancy.
The results were published in Transfer of Fetal Cells with
Multilineage Potential to Maternal Tissue. The team working on that
research included Kiarash Khosrotehrani, Kirby L. Johnson, Dong
Hyun Cha, Robert N. Salomon, and Diana W. Bianchi. The researchers
reported that the fetal cells passed to a pregnant woman during
pregnancy could develop into multiple cell types in her organs. They
studied these differentiated fetal cells in a cohort of women
fighting different diseases. The researchers found that the fetal
cells in the women differentiated into different cell types under
the influence of maternal tissues, and that those differentiated
cells concentrated in the tissue surrounding diseased tissues.
According to the team, this response could be a therapeutic response
to the disease in the once pregnant woman. The research indicated the long
lasting effects of pregnancy in a woman's body.

Fetus in fetu is a rare variety of parasitic twins , where the developmentally abnormal parasitic twin is completely encapsulated within the torso of the otherwise normally developed host twin. In the late eighteenth century, German anatomist Johann Friedrich Meckel was the first to described fetus in fetu, which translates to “fetus within fetus.” Fetus in fetu is thought to result from the unequal division of the totipotent inner cell mass , the mass of cells that is the ancestral precursor to all cells in the body. The unequal division is thought to occur during the formation of the blastocyst, which can also result in parasitic and conjoined twins . Fetus in fetu represents a developmental anomaly that has prompted developmental biologists to further examine the mechanisms for how twins arise.

Michael R. Harrison worked as a pediatric surgeon in the US throughout the late-twentieth century and performed many fetal surgeries, including one of the first successful surgeries on a fetus in utero, or while it is still in its gestational carrier’s body, also called open fetal surgery. A fetus is an organism developing inside of the uterus that is anywhere from eight weeks old to birth. Harrison hypothesized that open fetal surgery could correct developmental defects that may become fatal to the fetus at birth. After years of research, Harrison and his colleagues at the University of California, San Francisco, in San Francisco, California, performed surgery on the fetus of a woman in her seventh month of pregnancy to correct the fetus’s developmental defects. The surgery was successful, as the fetus developed into a healthy child. Harrison’s work led to advancements in fetal treatment techniques, such as a method to conduct open fetal surgery that will not harm the fetus or pregnant woman, as well as the establishment of one of the first fetal treatment centers in the US.

In 1996, Michael R. Harrison published “Fetal Surgery” in the American Journal of Obstetrics and Gynecology. In the article, Harrison describes the importance of fetal surgery and the techniques used to correct defects in fetuses. As a fetus develops in the uterus, it can develop abnormalities that may become debilitating or fatal. Harrison discusses cases that show how physicians can use fetal surgery to repair such abnormalities, including obstructions in the heart or urinary tract, or organs or muscles whose malformations impair function. Harrison states where knowledge is lacking within the field or where surgery would be inappropriate, such as in the modification of a cleft lip, which can be fixed after birth and as such does not merit the risks of surgery. In the article, Harrison provides a summary of what information existed about fetal surgeries in 1996, which helped physicians explore fetal surgery and make further advancements.

Rh incompatibility occurs when a pregnant woman whose blood type is Rh-negative is exposed to Rh-positive blood from her fetus, leading to the mother s development of Rh antibodies. These antibodies have the potential to cross the placenta and attach to fetal red blood cells, resulting in hemolysis, or destruction of the fetus 's red blood cells. This causes the fetus to become anemic, which can lead to hemolytic disease of the newborn. In severe cases, an intrauterine blood transfusion for the fetus may be required to correct the anemia.

In 2003, the Texas state legislature passed the Woman’s Right to Know Act, hereafter the Act, as Chapter 171 of the state’s Health and Safety Code. The Act sets requirements that physicians must follow during the informed consent process for abortion, or a medical procedure to terminate pregnancy, in Texas. Lawmakers amended the Act and added several additional regulations that restrict access to abortion in 2011, 2013, 2015, and 2017. For instance, the Act requires that physicians perform abortions after sixteen weeks of pregnancy in ambulatory surgical centers or hospitals and states that physicians must perform an ultrasound to view images, called sonograms, of a developing fetus inside a woman’s uterus before a woman may receive an abortion. The Act further requires practitioners and clinics to offer state-developed informational materials to women who seek an abortion. The Act placed several restrictions on abortion care in Texas, making it more difficult for women to access safe and legal abortion care, which opponents have challenged in courts.

Nuclear magnetic resonance imaging (MRI) is a technique to create a three-dimensional image of a fetus. Doctors often use MRIs to image a fetuses after an ultrasound has detected an, or has been inconclusive about an, abnormality. In 1983 researchers in Scotland first used MRI to visualize a fetus. MRIs showed a greater level of fetal detail than ultrasound images, and researchers recognized the relevance of this technique as a means to gather information about fetal development and growth. Researchers later used the technology to take measurements of the uterus, placenta, amniotic fluid, and fetus during the first trimester of pregnancy. MRI provided doctors with a non-invasive method to diagnose and treat fetal abnormalities and maternal conditions such as pre-eclampsia.

In 1980 the US National Institutes of Health (NIH) and the US National Institute of Child Health and Human Development (NICHD) released a report titled, “National Institutes of Health Consensus Development Conference Statement September 22–24, 1980.” The report lists recommendations for birth delivery through cesarean sections, a surgical procedure used to deliver the fetus via the pregnant woman’s abdomen. The recommendations arose from the 1980 Consensus Development Conference on Cesarean Childbirth in Bethesda, Maryland. Medical professionals, consumers, and biomedical research scientists attended the conference, and the NIH’s taskforce on the subject helped facilitate discussions regarding the safety of cesarean sections. The NIH taskforce concluded that cesarean section rates can be decreased and possibly reversed in addition to improving maternal and fetal outcomes and provided recommendations for future research on cesarean sections.

Among his myriad scientific and artistic contributions, Leonardo da Vinci's work in embryology was groundbreaking. He observed and diagramed the previously undemonstrated position of the fetus in the womb with detailed accompanying annotations of his observations. Leonardo was highly paranoid of plagiarism and wrote all of his notes in mirror-like handwriting laden with his own codes, making his writing difficult to discern and delaying its impact. Although he carried out his studies in embryology from 1510-1512, it was not until the 1900s that his work was popularized among the scientific community. Leonardo's embryological annotations found in the third volume of his private notebooks represent his notable contributions to and explanations of human development and embryology.