Question: Can you get pregnant if you have dry sex with your partner and you both are wearing sweatpants or underwear? What if they get a little wet?
In order for a woman to become pregnant from sex play with a partner, a man’s sperm must make their way to her ovum (also called an egg). This means that at the very least one needs sperm and an egg.
If the sperm find their way to the egg and fertilize the egg, then they next need to implant themselves into a woman’s uterus before a pregnancy can begin.
A Pretty Unlikely Scenario
If you think about it this way, and then think about the situation you are describing, it would be very difficult/near-impossible for sperm to get into a woman’s vagina if both partners are wearing clothing.
Although sperm are quite small, they typically do not make it through most types of clothing unless, of course, both partners were wearing mesh clothing or other clothing with large holes in it, or if they pushed their underwear to the side or were wearing thong underwear and thus somehow had direct genital contact.
However, in most cases, pregnancy is not possible from dry sex in which both people are wearing clothes.
Vaginal Wetness And Pre-Ejaculate
The wetness that you feel could be due to one or both partners. It is common for women to notice vaginal wetness as they become more sexually excited and aroused. This is as a result of natural vaginal lubrication which increases during arousal and can make sexual play more comfortable and pleasurable for women.
Also during sexual excitement and arousal, some men experience noticeable amounts of pre-ejaculate coming out of the tip of their penis. Total volume of pre-ejaculatory fluids can range from 0.2mL to 5mL, a considerable difference from person to person. 
Although research is conflicting as to whether pre-ejaculate contains any (or, if any, then many) sperm, it can still pass sexually transmissible infections, or STIs, as can vaginal fluids. And pre-ejaculatory fluids just might pose a pregnancy risk, even if only a small one. As such, people should avoid contact with each other’s genital fluids if they are not sure of each other’s STI status or if they don’t want to risk pregnancy.
Ultimately, to reduce the risk of pregnancy, it’s wise to consider either abstaining from sexual activity or using highly effective methods of birth control such as the IUD, birth control implant, birth control pill, birth control shot, condoms, or other methods. Some people even choose two methods – for example, condoms plus the IUD or condoms plus the pill (especially since condoms offer STI risk reduction in addition to pregnancy risk reduction).
Updated on April 30, 2017 to include additional research and contraceptive options.