Yes, partial penetration even an inch inside the vagina can cause pregnancy. Though, the chances are small but pregnancy can occur without penetration. All that is required is for a sperm to fertilize an egg. Thus, ejaculation on the vaginal opening or even the insertion of a finger with fresh sperm into the vagina can result in the fertilization of any mature egg waiting in the fallopian tube. This is possible as sperm can stay alive outside the body for one or two hours.
Ovulation & Fertilization
Pregnancy occurs when a man’s sperm enters a woman’s vagina, travels to her oviduct or fallopian tubes and fertilize a mature egg. A woman must ovulate (release a mature egg from her ovary) for her to become pregnant. During the ovulation period, the woman is said to be fertile and is likely to get pregnant if the released egg is fertilized. The uterus has two ovaries and each of them consists of follicles which are small sacs filled with fluid. These follicles grow and release an egg each month, usually two weeks before a woman’s monthly period. The follicle from where the egg erupted develops into corpus luteum which releases a hormone that thickens the lining of the uterus.
Fertilization occurs in the fallopian tube of a woman. The released egg moves into the fallopian tube where it awaits a sperm for 24 hours. If a sperm gets into the fallopian tube, it fuses with the egg. Thus, the fusion of an egg and the sperm is known as fertilization. The fertilized egg changes such that it cannot be penetrated by another sperm. Then, it moves to the uterus for implantation. Conversely, a sperm may not be available to fertilize a mature egg during a woman’s fertile days. In such a situation, the egg continues its journey to the uterus where it disintegrates and the risen hormone level returns to normal. If this happens, and the thick lining of the uterus is shed and the woman’s menstrual period starts.
The attachment of a fertilized egg to the walls of the uterus is known as implantation. A fertilized egg can stay up to 3 or 4 days in the fallopian tube before it gets to the uterus. However, it starts dividing and forms a mass of cells within 24 hours of fertilization. When it gets to the uterus, it attaches itself to the lining of the uterus. This action can cause slight bleeding or spotting in some women. The walls of the uterus become thicker and mucus seals the cervix until when the baby is due for delivery.
Possibility of Pregnancy from Partial Penetration
There are chances that pregnancy can result from partial penetration, though it may not be as high as when ejaculation occurs during sexual intercourse. The presence of sperm anywhere near a woman’s vagina can lead to pregnancy if the woman is fertile. Contact between the vaginal area and the penis even without penetration can introduce sperm cells into the vagina. Often, sperm cells make their way to the vagina during foreplay. This is possible as sperm cells from residual semen can be released during such moments. Residual semen may exist in a man’s genital tract if he has previously ejaculated and has not urinated after the ejaculation. Urination can cause sperms in such semen to be washed out. Thus, sperm cells from residual semen released on the vaginal area during foreplay may result in pregnancy if the woman is fertile. As sperms can stay alive in the vagina for about 3 to 5 days, there is a probability that a girl can become pregnant without penetration by a male genital.
Though, it is not likely that pregnancy can result from seminal fluid but it is possible as this fluid may contain viable sperm cells. This fluid can enter the vagina if it is partially penetrated by the penis or the fluid may get to the vaginal area during foreplay. Also, sperms can get into the vagina if the vagina is fingered with fingers smeared with semen or seminal fluid.Thus, the presence of sperms on the vaginal opening or its surroundings may lead to pregnancy even when the hymen is still intact.
The risk of pregnancy through partial penetration or even ejaculation on the vaginal area can be prevented by using barriers such as condoms. However, underwears such as panties cannot prevent the passage of sperms. Pregnancy can still result if partial penetration occurs through panties.