|William Dewees (from Wikipedia)|
Dewees starts out his chapter on pregnancy by explaining why it is important to scientifically determine whether a woman is pregnant or not. The reasons are essentially as follows:
1. So if the woman needs to be treated for some other disease, she doesn't get prescribed something that would hurt her or the baby if pregnant.
2. Because if she is under trial or awaiting execution, pregnancy might forestall it.
3. If the predicted date of birth might influence the 'character or property' of someone else.
So yes, clearly it is important to know if a woman is pregnant.
So how do you tell in the 1800s when no pee-sticks with plus signs were available? Not surprisingly, the first way is 'she doesn't have her period.' However there is clearly some debate in the field at this time.
Other things can 'suppress the menses' and sometimes a woman can bleed while pregnant.
Dewees spends excessive words and semi-colons defending his position on the subject:
"In declaring that women may menstruate after impregnation, I have no favourite hypothesis to support; nor am I influenced by any affectation or vanity to differ from others; neither do I believe I am more than ordinarily prone to be captivated or misled by the marvellous; for I soberly and honestly believe what I say, and pledge myself for the fidelity of the relation of the cases I adduce in support of my position." *
So you need some other signs of pregnancy other than just not menstruating. Next up: Nausea and Vomiting. Though "far from certain" as a sign of pregnancy, in conjunction with other signs, it is 'added proof'
Another sign is the enlargement of the sebaceous glands (which are on the areolae around the nipple), and the formation of milk. But milk coming in is also not certain:
"I once new a considerable quantity of milk form in the breasts of a lady, who though she had been married a number of years had never been pregnant; but who at this time had been two years separated from her husband. She mentioned the fact of her having milk to a female friend, who from an impression that it augured pregnancy, told it to another friend, as a great secret; and thus, after having enlisted fifteen or twenty to help them keep the secret, it got to the ears of the lady's brother. Her surprise was only equaled by his rage; and, in a paroxysm, he accused his sister, in the most violent and indelicate terms, of incontinency, and menaced her with the most direful vengeance." *
It turns out the lady was not pregnant, but was sick with 'phthisis pulmonalis.'
So finally the surest signs of pregnancy are the enlargement of the uterus and abdomen, and feeling the baby move "quickening".
(also mentioned are the 'pouting of the navel' and the 'spitting of frothy saliva')
*All quotes from Treatise on the Diseases of Females by William P. Dewees
For more on historical pregnancy medicine, see some great posts from Tea in a Teacup.