Weeks 1 and 2 – Gestational Age
Your menstrual cycle has just concluded, and your body is gearing up for ovulation. For most women, this occurs approximately 11 to 21 days after the first day of their last period. During sexual intercourse, millions of sperm are released into the vagina. These sperm journey through the cervix and into the fallopian tubes. If fertilization occurs, a sperm penetrates the egg, forming a unique set of 46 chromosomes known as a zygote, the foundation for a new human being. The fertilized egg travels for a few days through the fallopian tube, dividing into cells and forming a morula. This morula transforms into a blastocyst, eventually reaching the uterus. About 6 to 12 days post-fertilization, the blastocyst implants itself into the uterine lining, marking the beginning of the embryonic stage.
Week 3 – Gestational Age (Development of Your Baby – Week 1)
At this stage, the embryo undergoes significant foundational growth, initiating the development of the brain, spinal cord, heart, and gastrointestinal tract.
Weeks 4 and 5 – Gestational Age (Development of Your Baby – Weeks 2 and 3)
Limb buds for arms and legs emerge, though they are not yet distinctly formed. The heart has begun to beat steadily, and the placenta starts to develop, producing crucial hormones such as hCG. Basic blood circulation begins in the main vessels, and initial structures for the eyes and ears are forming. By the end of these weeks, the embryo measures about a quarter of an inch long.
Week 6 – Gestational Age (Development of Your Baby – Week 4)
The formation of the lungs, jaw, nose, and palate commences. The hand and foot buds, now webbed, will eventually develop into fingers and toes. The brain continues to evolve into its complex structures. A vaginal ultrasound may detect an audible heartbeat, and the embryo is about 1.5 inches long.
Week 7 – Gestational Age (Development of Your Baby – Week 5)
At seven weeks, all essential organs have started to develop, although the embryo still weighs less than an aspirin. Hair follicles, nipples, eyelids, and the tongue are in the early stages of formation. The trunk begins to straighten, making the elbows and toes more pronounced.
Week 8 – Gestational Age (Development of Your Baby – Week 6)
External and internal ear structures continue to form. All components present in an adult human are now represented in the small embryo. Bone formation is underway, and muscle contractions begin. Facial features mature, and eyelids develop further. The embryo reaches the end of its embryonic stage and enters the fetal period, measuring approximately 1 inch in length, about the size of a grain.
Weeks 9 to 13 – Gestational Age (Development of Your Baby – Weeks 7 to 11)
By this time, the fetus has grown to about 3 inches long and weighs approximately an ounce. Genitalia have developed into clear male or female forms, although they may not yet be visible on an ultrasound. The eyelids are closed and will remain shut until around week 28 of the pregnancy. The fetus can make a fist, and the first milk teeth buds are visible. The head is nearly half the size of the entire fetus.
For additional insights into pregnancy, you can explore the second and third trimesters of pregnancy.
In summary, the first trimester is a crucial period of rapid growth and development for your baby, laying the groundwork for all major systems and structures.
For those considering home insemination options, you can check out Make a Mom for innovative solutions, such as their re-usable insemination kit, or learn more about the process at How It Works. Additionally, for those interested in sperm donation, Vegas Pregnancy offers a free matching service. It’s also beneficial to read more about breast changes during pregnancy at Milk Makin Marvels. For comprehensive information on donor insemination, refer to American Pregnancy. Lastly, Modern Family Blog provides valuable insights into parenting and family dynamics.