乍得威克氏征象是怀孕的早期医学征象之一，是指因血流量增加，阴道、阴唇及子宫颈呈蓝紫色的情形，最早会在受精后六至八周出现

乍得威克氏征象最早是在1836年由法国医生艾蒂安·约瑟夫·雅克曼（Étienne Joseph Jacquemin，1796-1872）发现 ，此征象得名自詹姆斯·瑞德·乍得威克，他在一篇论文中提及此征象，认为雅克曼是第一个发现此征象的人，乍得威克在1886年在美国妇产科学会前读了此论文，并在第二年出版。

Chadwick's sign is a bluish discoloration of the cervix, vagina, and labia resulting from increased blood flow. It can be observed as early as 6 to 8 weeks after conception, and its presence is an early sign of pregnancy.

These color changes were discovered in approximately 1836 by French doctor Étienne Joseph Jacquemin (1796-1872), and are named after James Read Chadwick, who drew attention to it in a paper read before the American Gynecological Society in 1886 and published in the following year, wherein he credited Jacquemin for their discovery.