胎儿发展时间表
虽然令人困惑,但是医师通常将最后一次月经开始时视为怀孕第一天,这称为月经年龄,约在实际受孕前两周,所以整个时间表,胎儿发展比怀孕周数慢2周。

4 周
细胞已经分化,授精卵外层成为神经系统、皮肤和毛发。内层将变成呼吸与消化器官。中间层变成骨骼、肌肉、循环系统、肾脏与性器官。此时,验孕棒通常显示怀孕了。

 fetal development at 4 weeks

Medical Review: Reviewed by Matthew Hoffman, MD on October 28, 2008

SOURCE DOCUMENTATION: Williams Obstetrics 21st edition.

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