- 1.
Obesity continues to be a major public health concern across the globe.
- 2.
The prevalence of obesity has doubled over the past 30 years with 15% of women worldwide classified as obese as of 2014.
- 3.
It is reported that obese women have less contraceptive usage, more contraceptive failure, and lower intake of preconceptional folic acid, which can greatly compromise prepregnancy and pregnancy care.
- 4.
Prevention of untimed pregnancy in obese women is a major priority for health care professionals.
4.1
Risks associated with obesity during pregnancy
Maternal obesity is linked with a range of serious maternal and foetal outcomes
- 1.
Miscarriage
- 2.
Preterm delivery
- 3.
Gestational diabetes and metabolic syndrome of pregnancy
- 4.
Pregnancy-induced hypertension
- 5.
Preeclampsia
- 6.
Venous thromboembolism
- 7.
Induction of labour
- 8.
Prolonged labour
- 9.
Caesarean section
- 10.
Postpartum haemorrhage
- 11.
Wound infection
- 12.
Macrosomia
- 13.
Birth injury (shoulder dystocia)
- 14.
Stillbirth
- 15.
Neonatal death
4.2
Classification of obesity
| BMI | Classification |
|---|---|
| <18.5 | Underweight |
| 18.5–24.9 | Normal weight |
| 25.0–29.9 | Overweight |
| 30.0–34.9 | Class I obesity |
| 35.0–39.9 | Class II obesity |
| ≥40.0 | Class III obesity |
4.3
Metabolic disorders associated with obesity in nonpregnant obese
- 1.
Metabolic syndrome
- 2.
Diabetes mellitus
- 3.
Essential hypertension
- 4.
Cardiovascular disease including myocardial infarction,
- 5.
Venous thromboembolism
- 6.
Breast cancer
- 7.
Endometrial cancer
- 8.
Changes in the metabolism of sex steroids used in hormonal contraception
- 9.
May influence half-life, clearance (area under the curve), and time to reach steady state
4.4
Mechanisms by which obesity could potentially affect contraceptive efficacy
- 1.
Obesity can have profound effects on different physiologic processes, including absorption, distribution, metabolism, and excretion of contraceptive drugs.
- 2.
Obesity is also associated with altered body composition with an increase in fat mass, which can affect the distribution of hydrophilic and lipophilic drugs.
- 3.
Other physiological alterations in obesity that can have a potential impact in contraceptive drug metabolism and excretion include increased splanchnic and renal flow.
- 4.
In spite of all the potential mechanisms by which obesity could affect contraceptive efficacy, there have been few studies to date that have investigated the pharmacokinetics of contraceptive steroids in obese women.
4.4.1
How obesity may affect contraceptive efficacy?
- 1.
In one study, the half-life of levonorgestrel (LNG) in obese subjects was twice that of normal BMI subjects.
- 2.
In one study of oral contraceptives, obese women had a lower area under curve and lower maximum value for ethinylestradiol than normal weight women.
- 3.
In a longitudinal study of depot Medroxy progesterone (DMPA) in different classes of obese women, median MPA was consistently lowest among class 111 obese women, but above the levels needed to inhibit ovulation.
- 4.
European Society of Contraception has concluded that there is no robust evidence for decreased efficacy of different contraceptive methods in overweight or obese women.
4.5
Potential concerns with obesity and contraception
- 1.
Historically, overweight and obese women have been excluded from trials in contraception, leading to a lack of robust evidence.
- 2.
As a generalisation, women tend to blame contraception for weight gain. This perceived weight gain is a leading cause of discontinuation of contraception at least in some parts of the world.
- 3.
Obesity doubles the risk of venous thromboembolism as compared with someone with a normal BMI.
- 4.
In principle, choice for contraception should take account of possible adverse metabolic effects associated with various hormonal methods of contraception,
- 5.
Procedure-dependent contraceptive methods [intrauterine devices (IUDs) and sterilisation] are technically more challenging to perform in an obese woman than their normal BMI counterparts.
4.5.1
Contraceptives and weight gain
- 1.
Many women and clinicians worldwide believe that an association exists between weight gain and oral contraceptives.
- 2.
Perception about weight gain can also lead to early discontinuation among users of contraception.
- 3.
More importantly, most of those who discontinued, failed to adopt another method of contraception, exposing themselves to an increased risk of pregnancy,
- 4.
Weight gain is due to one of the following factors: fluid retention, fat deposition, or muscle mass.
- 5.
A causal relationship between combined oral contraceptives and weight gain has not been clearly established.
- 6.
Progestogen-only contraception is ideally suited for women who have contraindications to or who are unable to tolerate oestrogens.
- 7.
There is limited evidence for weight gain when using progestogen-only contraception.
4.5.2
Potential mechanisms by which contraceptives can cause weight gain
- 1.
Treatment with hormonal contraceptives may lead to activation of renin–angiotension–aldosterone system.
- 2.
Fluid retention may be induced by the mineralocorticoid activity of contraceptive steroids.
- 3.
Oestrogens increase the size and number of subcutaneous adipocytes, which can be associated with increased subcutaneous fat in breast, hips, and thighs.
- 4.
The anabolic properties of COCs can have an effect on satiety and appetite that could result in increased food intake and weight gain.
- 5.
A Cochrane review of 49 studies, however, did not find any large association between oral COC and weight gain.
- 6.
Some longitudinal studies have suggested that the perceived weight gain with COC may be related to the natural changes in weight from a lifetime perspective.
- 7.
In a Cochrane review of oral progestogen contraceptives, mean weight gain at 6 and 12 months was less than 2 kg for most studies.
- 8.
There is some evidence that obese adolescent users of DMPA may gain more weight compared to those with normal weight.
4.5.3
Safety of hormonal contraceptives in obese women
4.5.3.1
Cardiovascular disease
- 1.
Obesity is associated with an increased risk of different health conditions, including diabetes mellitus, dyslipidaemia, heart disease, stroke, venous thrombo-embolism, hepatobiliary disease, and cancer.
- 2.
Current users of oral contraceptives had a moderately increased risk of hypertension.
- 3.
Some studies report that oral contraceptives may be associated with an increased risk of myocardial infarction and stroke is more marked in obese women, especially if they smoke heavily.
- 4.
A systemic review evaluating the effects of CHC use in women with BMI>30 on MI and stroke reported inconclusive and conflicting evidence.
4.5.3.2
Venous thromboembolism
- 1.
Exogenous oestrogens and obesity may increase blood coagulability with an increase in procoagulant factors (factors VII, VIII, XII, fibrinogen).
- 2.
Oral contraceptives among smokers may be associated with increased levels of fibrinogen and intravascular fibrin deposition and may also increase risk of arterial thrombosis.
- 3.
The risk of VTE increases in obese women (especially with BMI >35) and the use of combined oral contraceptives (3.46 times increased risk).
- 4.
It appears that the risk of VTE is associated with higher dose ethinylestradiol (>50 µg).
- 5.
There is no evidence for increased risk of VTE with progestogen-only pill.
4.5.3.3
Cancer
- 1.
Oral contraceptive use has been associated with increase in risk of cervical cancer.
- 2.
There are conflicting results with breast cancer and the use of COC.
- 3.
This increased risk of cervical and breast cancer among current users appears to be lost within 5 years of stopping oral contraceptive.
- 4.
There is a decrease in risk of ovarian, uterine, and colorectal cancers.
- 5.
On balance, many women benefit from significant reductions in risks of certain types of cancer that seems to persist many years after stopping treatment (lymphatic and haematopoietic cancers).
- 6.
Obesity, per se, has been associated with increased risk of cancer, especially breast, endometrial, ovarian, and colorectal.
- 7.
It is, therefore, theoretically possible that oral contraceptive use in obese women may have significant effects on incident cancer.
The UKMEC criteria (2016) for contraceptive use clearly outlines the criteria for contraceptive use in obesity .
UKMEC criteria (2016) for contraceptive use—obesity and selected clinical conditions that are of particular relevance to obese women.
