Many women are concerned with how much weight they should be gaining each month rather than the broad picture (which is between 25-35 pounds). It is hard to accurately define the exact amount of weight you will gain each month because every woman is different. Some women put on more of their weight during the first and second trimesters, whereas others put on the most amount of weight during the third trimester.
If you need to break down your weight gain, it is easier to keep track of things if you consider your pregnancy during trimesters rather than months.
During the first trimester (roughly months 1-3) most women will gain an average of 1-5 pounds total. Many women are so sick with morning sickness during the first trimester that they have a hard time gaining any weight. Now remember, this rule is not hard and fast. If you are eating healthily and consuming plenty of fruits and vegetables, but find that you are gaining more weight than this, chances are you are still perfectly normal. You should consult with your healthcare provider if you have any questions or concerns.
During the second trimester or months 4-7, most women will gain on average about 1 pound per week. Weight gain will sometimes taper off in the third trimester or last couple of months, with most women gaining about ½ pound per week. Keep in mind however that some women will still gain about 1 pound per week sometimes more during the last trimester as their babies put on fat and their bodies prepare for the labor and delivery process