Can Intercourse Assist With Assisted Reproductive Technology (ART)
Assisted reproductive technology (ART), also known as in vitro fertilization (IVF) where an egg and sperm meet in a laboratory petri dish is about as far from a natural conception as you can get. Since it was first proposed in the late 1980’s, there is a growing body of evidence that suggest this high-tech treatment can be enhanced with some old fashion intercourse. A recent article by Crawford et al., published in the journal Human Reproduction, took an in-depth look at this question by examining all of the past randomized clinical trials on seminal fluid and ART outcomes.
In a successful pregnancy, the uterine lining or endometrium is the where a newly formed embryo will attach and then implant and eventually grow into a viable fetus. As it turns out, this endometrium is a very immune rich environment. The allogenic (similar but immunologically foreign) embryo induces a modified maternal immune response that allows for successful implantation and growth. Seminal fluid (male ejaculate) has been shown to enhance this maternal immune tolerance and thus assist with implantation in both animal and human studies.
Only 2% to 5% of the male ejaculate (seminal fluid) is comprised of sperm. The remainder of the seminal fluid devoid of sperm is referred to as the seminal plasma. The seminal plasma is derived in close to equal parts from the prostate gland and the seminal vesicle. This plasma has traditionally be thought of as a transport and nutrient medium for the sperm, facilitating their survival in the acidic vagina, and allowing their progression into the uterine cavity. The seminal plasma is also rich in various signaling agents that induce an inflammatory response that activates pre-implantation immune changes in the female reproductive tract. One of the principle signaling agents is a protein called transforming growth factor beta (TGF-β) which is thought to play an key role in preparing the female immune system for embryo implanation. While the cervical mucus acts as a barrier to most of the ejaculate, several studies have demonstrated that albumin microspheres placed at the opening of the cervix will reach the fallopian tubes within 1 minute due to subendometrial uterine peristaltic contractions. These contractions and the movement of microspheres into the female reproductive tract is most pronounced at mid cycle, around the time of ovulation. Following intra-vaginal ejaculation, it is postulated that these peristlatic waves move the seminal plasma through the cervix and the uterine cavity where its package of signaling factors can affect endometrial receptivity. There is evidence that the seminal plasma is also taken up by the female lymphatic system, further stimulating the female reproductive immune system.
Benefits of Seminal Fluid and ART
The analysis by Crawford et al. identified seven randomized clinical trials that looked at the influence of seminal plasma and pregnancy rates with IVF. These trials investigated outcomes associated with exposure to seminal plasma at the time of oocyte retrieval and/or around the time of embryo transfer. Exposure to seminal fluid varied from unprotected vaginal intercourse to intravaginal, intracervical or intrauterine injection. In order to gain more insight, the authors pooled the results of these studies in a meta-analysis. With over 2000 analyzed, the authors found a significant improvement in clinical pregnancy rates when women were exposed to seminal plasma during their IVF treatment cycles. Only two of these trials evaluated ongoing pregnancy rates after exposure to the seminal plasma. In either the individual studies or when pooling the results of these studies, no difference could be found in this parameter.
Risks of Seminal Fluid and ART
The primary risk of having intercourse during an IVF cycle is conceiving multiple pregnancies. It is well established that there is a 2 to 12 fold increase incidence of monozygotic (identical) twinning with the use of ART. In addition, there are numerous reports of multiple hetero-zygotic (non-identical) pregnancies in ART resulting from concurrent natural conception. While the exact incidence is not known, a recent review and analysis by Osianlis et al. published in 2014 in the journal Human Reproduction, found that as many as 1 in 5 twin pregnancies following a single embryo transfer, was the result of conception from unprotected intercourse. Multiple pregnancies increase the risk for adverse obstetrical outcomes and when unexpected, are quite upsetting for couples. In addition, research has shown that there may be a small risk of infection with unprotected intercourse after IVF procedures. Finally, several researchers have voiced concern, that uterine contractions with intercourse timed around embryo transfer may be detrimental to implantation.
In natural conception, the interaction of the male and female reproductive system is quite remarkable, often resulting in a miraculous outcome. In this complex and beautifully orchestrated event, it is not surprising that the male ejaculate may play a significant role in enhancing implantation rates. Hopefully, more studies will be forthcoming to help define the optimal timing and modality of seminal plasma exposure in enhancing ART outcomes. While unprotected intercourse may be beneficial, a word of caution is warranted for those patients who are at risk of fertilizing an ovulated oocyte during a stimulated IVF cycle or a natural cycle using cryopreserved embryos.
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