Fetal Development: From Conception to Birth
Pregnancy is an incredible journey, and understanding how your baby grows can help you feel more connected and confident throughout each stage. From the moment of conception to the moment you give birth, your baby is developing rapidly. Here’s an overview of fetal development, trimester by trimester.
First Trimester (Weeks 1–12)
At conception, all of your baby's DNA is present when a single-celled zygote is formed from the sperm and egg. This initial cell contains the complete set of chromosomes from both parents, making up the baby's unique genetic blueprint, which will guide its growth and development throughout life. After conception, the fertilized egg travels to the uterus and implants, beginning rapid cell division. By week 5, the tiny embryo forms the heart, brain, and spinal cord. Around weeks 6–7, the heartbeat can often be detected on an ultrasound. A baby's external genitalia begins to form around this time though it is not visually distinct until around 9-12 weeks. By week 10, major organs have begun forming, and small features like eyelids, fingers, and toes start taking shape. At the end of the first trimester, your baby is about the size of a lime and already moving, even if you can’t feel her or him yet.
Second Trimester (Weeks 13–26)
Often considered the most comfortable stage of pregnancy, the second trimester is when many women start to feel the baby’s movement—called “quickening”—around weeks 18–20. During this time, your baby grows rapidly. Facial features become distinct, and by week 20, an anatomy scan can often reveal the baby’s sex. The senses also develop, allowing the baby to hear your heartbeat and even respond to sounds. By week 26, the baby’s lungs, eyes, and brain continue maturing, and a protective coating called vernix forms on their skin.
Third Trimester (Weeks 27–40)
In the final trimester, your baby gains weight quickly and prepares for life outside the womb. By week 32, the baby can open and close his or her eyes, practice breathing movements, and respond to light. Around week 36, most babies move into a head-down position for birth. During the last few weeks, the lungs fully mature, body fat increases, and the baby settles into the pelvis as your body prepares for labor.
If you’re pregnant or think you might be, you don’t have to navigate this journey alone. Our professional team is here with confidential, compassionate care, free services, and reliable information. Pregnancy is an amazing time of growth. We’re here to help you along the way.
Contact us today to schedule an appointment for a free pregnancy test and free ultrasound. Call or text (248) 471-5858 for free, confidential help. Si desea hablar con un miembro del equipo de AWPC en español, envíenos un mensaje de texto al (248) 471-5858.
