Yes. When Roe vs Wade was first established as the Constitutional interpretation of what was legal and medically ethical, docs back then were still measuring fetal development in trimesters. They at first said the limit was the end of the second trimester. Once technology began to help determine development of the fetus with better monitoring, and with the technological development of NICU equipment and techniques of ensuring the life of pre-term newborns, the age of viability has adjusted accordingly.
We now measure viability in weeks rather than in trimesters since 1973, and fetal viability has been determined roughly a few weeks earlier than before given technological advancement. It still is not a distinct hard line of "Fetus" one day and "Baby" the next (because just like us born-folk, every fetus develops at different rates).
Technological advances are sure to continue to develop, and medical ethics will - again - adjust accordingly. Hope that helps.