1. Pregnancy
  2. Pregnancy health
  3. Fetal development

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When Does a Fetus Become a Baby?

A baby is a baby, right? Well, not exactly. From the day your egg is fertilized to the day they enter the world, your little one goes through a number of unique developmental phases. So when does a fetus become a baby? Keep reading to find out. 

Let’s begin by exploring the various medical terms that define each stage of your pregnancy and their associated timelines.

The embryonic period is one of the earliest stages of development following fertilization. The egg and sperm unite, combining genetic material from both partners, before dividing into a multicellular organism called a zygote. The zygote travels to your uterus, where it attaches itself to the uterine wall in a process called implantation. This is effectively the beginning of pregnancy. Through the eighth week of gestation, this group of cells is known as an embryo.

Between weeks 6 and 7, the neural tube (the basis for your baby’s nervous system) closes and brain development begins. At this point, there is a detectable small flutter in the area that will eventually develop into a heart.

Eight weeks after conception, the embryo is defined as a fetus and enters the next period of growth. Technically, your future offspring is considered a fetus until the moment you give birth.

During the embryonic period, your baby’s major organ systems are slowly establishing themselves. After their formation, the organs continue to develop over the next several months, becoming increasingly complex and functional.

In this phase of development, the embryo’s heart will pump at roughly 165 beats per minute. As their neural tube, spinal cord, and brain progress, a face begins to take shape. Limbs emerge as small nubs and gradually elongate.

During the embryonic period, your baby’s major organ systems are slowly establishing themselves.

The embryonic period poses the greatest risk for birth defects, whether it’s due to poor maternal health or abnormalities in cell division. This is also the trimester when the majority of miscarriages occur, as it’s when the body may detect an unviable pregnancy and miscarry.

The major structures created in the embryonic stage will undergo significant expansion and start to mature during the fetal period, which includes the last part of the first trimester, and all of the second trimester and third trimester. It’s marked by rapid growth and very important developments. 

The major structures created in the embryonic stage will undergo significant expansion and start to mature during the fetal period, which includes the last part of the first trimester, and all of the second trimester and third trimester.

During this phase it’s recommended to get a checkup every month with an obstetrician who can monitor the fetus’ growth and confirm that their heartbeat is normal. The fetus’s genitals are far enough along to be visible at around week 16. However, biological sex is usually determined at the 20-week ultrasound. This doctor’s visit should include a comprehensive examination of your baby, in which each of their major body systems is evaluated.

Some will argue that a fetus becomes a baby at 12 weeks and others claim the line is crossed at 20 weeks. Biologically speaking, however, a pregnancy isn’t viable until 22–24 weeks. Advances in medical technology over the years have allowed scientists to observe fetal development much more closely. This has led to the usage of terms like zygote, embryo, and fetus to clearly delineate the various phases of growth.

The fetal period immediately follows the embryonic period and begins at the ninth week of pregnancy. Until the actual day of delivery, the official medical term for your baby is “fetus” (or “unborn offspring”). 

It’s perfectly normal for people to refer to their developing child as a baby, even before they’re pregnant.

On the other hand, some people don’t call a fetus a baby until they’re capable of surviving on their own outside the womb. From this standpoint, the fetus is a living organism, but not yet a “baby.”

This is an extremely complicated question, one that has been widely and fervently debated. Some define a fetus as a person at conception, while others say a fetus isn’t a person until it can survive outside the womb.

As medical science progresses, the point of viability outside the womb occurs earlier and earlier. In the 1970s, for example, viability was placed at 26 weeks. Now, with the availability of steroids to encourage growth and equipment to support underdeveloped lungs, viability is around 22–24 weeks.

Establishing personhood for a fetus is a practice fraught with political and legal implications that can endanger the lives of pregnant people. Personhood implies that your fetus has full human rights — the same as a baby, a teenager, or a senior citizen. 

Regardless of science or laws, a pregnant person has the right to refer to their unborn child using the language they’re most comfortable with. From conception to delivery, you and you alone have the freedom to choose how to refer to your future child. As the mother, you get to decide when your baby officially becomes a baby.

https://my.clevelandclinic.org/health/articles/7247-fetal-development-stages-of-growth

https://study.com/academy/lesson/what-is-a-fetus-growth-position-quiz.html

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3713799/

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