**6.2 Types**

Generally, most frequently used IUCDs are divided into two main categories: hormonal and non-hormonal. Various terms are used to describe IUCDs, including intrauterine device and intrauterine contraception; hormonal IUCDs or progestincontaining devices are also referred to as an IUS.

Copper IUCDs (Cu-IUCDs) are non-hormonal and vary in size and shape. They consist of a piece of plastic and copper, with some types containing silver or other metals. Theoretically, this may increase the longevity of the device; however, no evidence has been identified to confirm any clinical benefit of mixed-metal IUCDs over IUCDs that only contain copper. In addition to their use as long-acting, reversible forms of contraception, Cu-IUCDs can also be used as a method of emergency contraception [124, 125].

In turn, the LNG-IUS is a T-shaped device with an elastomer core containing LNG. There are different LNG-IUSs available which release a varying amount of LNG. In addition to its use for contraception, the LNG-IUS can be used in the management of heavy menstrual bleeding and as endometrial protection during estrogen replacement therapy [126].

### **6.3 Mechanism of action**

The IUCD has multiple mechanisms of action that contributes to its contraceptive properties. The device causes chemical changes that damage the sperm and ova before they can meet, thus preventing fertilization [127]. Moreover, copper ions released by Cu-IUCDs reduce sperm motility and viability and inhibit sperm penetration and migration by affecting the uterotubal fluid, thus decreasing the number of sperm reaching the oviduct and their capacity to fertilize the ova. Copper also induces changes in the endometrium, causing a cytotoxic inflammatory response increasing levels of white blood cells, enzymes, and prostaglandins in the uterine fluid, thereby impairing sperm function and preventing implantation. Additionally, Cu-IUCDs inhibit ova development [114, 128, 129].

The LNG-IUS inhibits fertilization by thickening the cervical mucus which acts as a barrier to the upper genital tract, as well as causing changes in the uterotubal fluid that impair sperm migration. Inhibition of implantation via endometrial changes is the secondary mechanism of action of the LNG-IUS. A foreign body effect may also be a contributing factor, as has been observed with other intrauterine methods [128, 130, 131]. While the LNG-IUS also has a minor effect on the hypothalamic pituitary ovarian axis, serum estradiol concentrations are not reduced, and the majority of women (>75%) continue to ovulate [132–135].

Progestogenic effects of the LNG-IUS on cervical mucus have been demonstrated, but it is not fully understood how quickly such changes are established [136–138]. Prevention of implantation occurs via a progestogenic effect on the endometrium [139–141]. Within

*Perspective Chapter: Modern Birth Control Methods DOI: http://dx.doi.org/10.5772/intechopen.103858*

1 month of insertion, high intrauterine concentrations of LNG induce endometrial atrophy [130, 131, 142–144]. The LNG-IUS also causes changes in the endometrium that may also contribute to its contraceptive effect, particularly by altering the intercellular junctions between the epithelial and stromal cells and increasing the number of phagocytic cells [140, 143, 145].

All of the anti-fertility actions of IUCDs occur prior to implantation [114, 128, 129, 146]. The common belief that the mechanism of action of IUCDs is the destruction of an implanted embryo is not supported by evidence. Studies of IUCD users were unable to find embryos or detect human chorionic gonadotropin, indicating that transient, or chemical, pregnancies had not occurred [128, 147, 148]. In summary, there is no evidence to suggest that IUCDs disrupt an implanted pregnancy [149].

#### **6.4 Effectiveness**

Failure rates within the first year of IUCD insertion are 0.6–0.8% for women with a Cu-IUCD and 0.2–0.9% for women with an LNG-IUS. The cumulative failure rate over 10 years of use of the Cu-IUCD is 2.1–2.8%, while that of the LNG-IUS over 5–7 years of use is 0.7–1.1% [150]. Unlike most other forms of reversible contraception, the IUCD does not rely on patient participation or adherence for correct usage; thus, failure rates for typical and perfect users are similar.

#### **6.5 Advantages**

The IUCD is one of the most cost-effective methods of long-acting, reversible contraception available; even though the cost of the device and insertion can be high initially, the overall cost with long-term use decreases with time because no additional expenditure is required [151]. Moreover, this method is highly effective, acts immediately, and is not dependent on user compliance as it does not require regular adherence to maintain its effectiveness. It requires only a monthly self-checking for strings, and yearly follow-up visits. In addition, the IUCD does not interfere with intercourse or breastfeeding and can be inserted 6 weeks after giving birth. Clients are assured of a rapid return of fertility upon removal. Depending on the type of IUCD inserted, women can avoid the use of either exogenous estrogen (both IUCD types) or hormones in general (Cu-IUCDs only).

#### *6.5.1 Non-contraceptive uses*

The IUCD offers a reduced risk of cervical, endometrial, and ovarian cancers [152–155]. Moreover, the LNG-IUS can be used in the treatment of menorrhagia, endometriosis, and pelvic pain [155–157].

#### **6.6 Disadvantages**

There are several disadvantages to the utilization of IUCDs. This type of contraceptive device requires the client to undergo a minor procedure for insertion and removal; as such, the client cannot discontinue use of this method on her own. Moreover, the client will need to check strings after each menstrual period. Pelvic examination and genital tract infection screening is mandatory before initiation of use, as per the Centers for Disease Control and Prevention guidelines. In addition, because she may experience heavier monthly bleeding, the device may contribute

### *Studies in Family Planning*

to anemia if the women has low iron stores prior to insertion [158, 159]. Finally, IUCDs do not protect against STIs.
