Final answer:
At 38 weeks after conception, the fetus is fully developed with mature organs, ready to be born. It has grown considerably, weighing between 2.7 and 4.6 kg (6-10 pounds), and measures about 51 cm (20 inches). Birth is imminent at this stage, and a baby born prior to this is considered premature.
Step-by-step explanation:
Development at 38 Weeks After Conception
At 38 weeks after conception, significant developments occur in the fetus. This is a critical time when the bones complete their development and the fetus experiences rapid growth and substantial increase in body fat. The previously wrinkled skin fills out due to the addition of subcutaneous fat layers. By the end of the 38th week, the fetus typically measures about 51 cm (20 inches) in length and weighs between 2.7 and 4.6 kilograms (6-10 pounds).
All of the fetus's organs have matured by this time, and it is fully prepared for birth. The fetus is considered full-term and is physiologically ready to adjust to life outside the uterus. If born before the 38th week, a baby is deemed premature. The average pregnancy lasts about 270 days from conception to birth with a due date generally set at 284 days from the last menstrual period, based on an estimated 14-day conception time frame.
The major developments during the final weeks involve the fetus rapidly putting on body fat and gaining weight, which is crucial for maintaining temperature and energy after birth. As the pregnancy reaches its full term, the pregnant person's body has gone through significant changes to accommodate the growing fetus, which now has all functioning organs and is ready for the birthing process.