胎兒發展時間表
雖然令人困惑,但是醫師通常將最後一次月經開始時視為懷孕第一天,這稱為月經年齡,約在實際受孕前兩週,所以整個時間表,胎兒發展比懷孕週數慢2週。

4 週
細胞已經分化,授精卵外層成為神經系統、皮膚和毛髮。內層將變成呼吸與消化器官。中間層變成骨骼、肌肉、循環系統、腎臟與性器官。此時,驗孕棒通常顯示懷孕了。

 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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