The process of fetal development is complex and well-organized. It starts before you are even aware that you are pregnant and concludes after your kid is born. Although most individuals don't use these terminology when discussing their pregnancies, knowing them might be useful.
| Stage | Duration | Key Events and Developments |
| Germinal Stage | Conception: 1 week | - When sperm fertilizes the egg to form a zygote - Zygote travels down the fallopian tube toward the uterus - Rapid cell division - Zygote transforms into blastocyst - Blastocyst implants into the uterine lining -Menstruation stops & Hormone production begins |
| Embryonic Stage | Conception: 3rd week to the end of the 8th week | - Blastocyst develops into embryo - Formation of neural tube (future brain and spinal cord) - Development of head, eyes, mouth, and limb buds - Heart cells begin pulsing (around week 5-6) - Most organs and systems begin to form - Morning sickness often starts |
| Fetal Stage | Conception: 9th week until birth | - Embryo is now called a fetus - Sex is assigned (not visible via ultrasound yet) - Major organs and systems continue maturing - Growth of fingernails, eyelashes, and hair - Fetus can move limbs (felt around week 20) - Most physical growth (weight and length) occurs |
Although the usual pregnancy (gestation) lasts 40 weeks, an unborn child spends around 38 weeks in the womb. This is due to the fact that pregnancy is measured starting on the first day of the woman's last menstruation, rather than the day of conception, which usually happens two weeks later.
Actually, the first day of your last menstrual period (LMP) marks the beginning of pregnancy. This is the fetus's gestational age. It happens around two weeks before actual conception. The first day of your last period may seem odd, but it will play a significant role in figuring out when you are due. In order to determine how far along you are in your pregnancy, your obstetrician will question you about this date.
| Trimester | Month | Key Developments |
| Month 1 | Fertilization and implantation; amniotic sac and placenta form | |
| First Trimester | Month 2 | Neural tube, heart, and facial features form; organs begin developing |
| Month 3 | Embryo becomes fetus; external features become recognizable | |
| Month 4 | Formation of vocal cords, external genitals; movements like sucking and stretching | |
| Second Trimester | Month 5 | Lanugo (fine hair) and vernix (protective coating) appear; first movements felt |
| Month 6 | Skin becomes red and translucent; fetus responds to sound | |
| Month 7 | Rapid brain development; lungs mature, baby opens eyes | |
| Third Trimester | Month 8 | Weight gain, fat deposits, bones harden, fetal movements decrease |
| Month 9 | Continued weight gain, maturation of lungs and brain, fetus prepares for birth |
| Trimester | Week | Key Developments |
| First Trimester | Week 1 | Fertilization and zygote formation |
| Week 2 | Embryo implants in the uterus | |
| Week 3 | Neural tube begins to form | |
| Week 4 | Heart begins to beat | |
| Week 5 | Limb buds appear; size of a sesame seed | |
| Week 6 | Brain waves detected; facial features begin | |
| Week 7 | Organs form; heart has four chambers | |
| Week 8 | Genitalia form; bones begin developing | |
| Week 9 | Now called a fetus; organs formed | |
| Week 10 | Fingernails and toenails form | |
| Week 11 | Baby moves; kidneys begin functioning | |
| Week 12 | Face forms; teeth buds appear | |
| Second Trimester | Week 13 | Baby grows; hair starts growing |
| Week 14 | Genitals formed; sucking motions start | |
| Week 15 | Baby moves; bones harden | |
| Week 16 | Heartbeat audible via stethoscope | |
| Week 17 | Skin thickens; skeleton hardens | |
| Week 18 | Eye movement; more noticeable kicks | |
| Week 19 | Vernix forms on skin | |
| Week 20 | Halfway mark; hair and lashes form | |
| Week 21 | Digestive system matures; baby swallows fluid | |
| Week 22 | Baby responds to sound | |
| Week 23 | Lung air sacs begin forming | |
| Week 24 | Baby starts practicing breathing | |
| Third Trimester | Week 25 | Eyes formed; baby hears and breathes in practice |
| Week 26 | Brain development speeds up | |
| Week 27 | Eyes open/close; more fat stores | |
| Week 28 | Lungs mature, but still developing | |
| Week 29 | More active; stronger movements | |
| Week 30 | Bones harden; skin thickens | |
| Week 31 | Lungs and brain grow rapidly | |
| Week 32 | Fat builds; baby moves head-down | |
| Week 33 | Weight and length increase; organs mature | |
| Week 34 | Brain and lungs nearly developed | |
| Week 35 | Weight gain; head may drop into pelvis | |
| Week 36 | Organs ready; fat continues increasing | |
| Week 37 | Full-term; baby prepares for labor | |
| Week 38 | Fully developed | |
| Week 39 | Gains fat; ready for birth | |
| Week 40 | Full-term; labor may start |
For a pregnancy to develop, progress, and ultimately result in safe delivery, a series of developmental milestones has to be achieved during the period of 9 months. It may be fascinating and enlightening to learn about the development of the fetus, particularly when you consider how many organs, systems, and bodily functions develop in just nine months.
Pregnancy brings about a lot of changes for both you and the developing fetus. If you have any questions about these changes or anything else, ask your pregnancy care provider. They are there to provide you with the finest treatment possible. Accurately tracking your pregnancy timeline is essential for monitoring fetal development and scheduling vital prenatal care.
Get expert guidance from Surya Hospitals.
Q1: How soon can I tell if I'm expecting?
A: The examination of HCG is the basis for most pregnancy tests. For the HCG to rise sufficiently for pregnancy tests to detect it, it usually takes three to four weeks from the first day of your last period.
Q2: When should I reach out to OB/GYN for my pregnancy?
A: Most doctors will ask you to wait until you get a positive home pregnancy test before scheduling an appointment. Once your body has enough HCG in your blood, these tests show very accurate results.
Q3: Which weeks are crucial for the growth of the fetus?
A: There are specific risks associated with each trimester or stage of pregnancy. It's challenging to determine which weeks are more or less significant. However, the majority of doctors will agree that the first 13 weeks of pregnancy (the first trimester) are the most critical period for fetal growth.
+91 8828828100
Previous
Next
