respiratory illnesses or other medical problems during the first two years of life. Some used adaptive equipment such as walkers or feeding tubes, but most could feed themselves when they were 2 years old. Most had typical vision and hearing. Period of viability Beliefs about viability vary by country. Medical decisions regarding the resuscitation of extremely preterm infants (EPI) deemed to be in the "grey zone" usually take into account weight and gestational age, as well as parental views. One 2018 study showed that there was a significant difference between countries in what was considered to be the "grey zone": the "grey zone" was considered to be 22 to 23 weeks in Sweden, 23 to 24 weeks in the UK, and 24 to 26 weeks in the Netherlands. Whether the fetus is in the period of viability may have legal ramifications as far as the fetus' rights of protection are concerned. Traditionally, the period of viability referred to the period after the twenty-eighth week.<ref>{{cite book| vauthors = Finney PA |url=https://archive.org/details/MoralProblemsInHospitalPractice|title=Moral Problems in Hospital Practice: a Practical Handbook.|date=1922|publisher=Herder Bk. Co|location=St. Louis|page=24|oclc=14054441}}</ref> United States Supreme Court The United States Supreme Court stated in Roe v. Wade (1973) that viability, defined as the "interim point at which the fetus becomes ... potentially able to live outside the mother's womb, albeit with artificial aid", "is usually placed at about seven months (28 weeks) but may occur earlier, even at 24 weeks." The 28-week definition became part of the "trimester framework" marking the point at which the "compelling state interest" (under the doctrine of strict scrutiny) in preserving potential life became possibly controlling, permitting states to freely regulate and even ban abortion after the 28th week. The subsequent Planned Parenthood v. Casey (1992) modified the "trimester framework", permitting the states to regulate abortion in ways not posing an "undue burden" on the right of the mother to an abortion at any point before viability; on account of technological developments between 1973 and 1992, viability itself was legally dissociated from the hard line of 28 weeks, leaving the point at which "undue burdens" were permissible variable depending on the technology of the time and the judgement of the state legislatures. Born-Alive Infants Protection Act of 2002 In 2002, the U.S. government enacted the Born-Alive Infants Protection Act. Whereas a fetus may be viable or not viable in utero, this law provides a legal definition for personal