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Obesity, Polycystic Ovary Syndrome and Fertility
studies carried out in different populations clearly showed the Figure 1: Effect of Exercise on Composition of
importance and complexity of the problem.
Weight Loss During Dieting
6
12
Studies in Women Attending Infertility Clinics
Loss of:
Lean mass
High bodyweight was associated with reduced fecundability in
10
Fat
women undergoing a donor insemination programme. In this study
the value of the waist/hip circumference ratio was shown to be a 8
more precise and linear indicator of the detrimental effect of
ams
overweight compared with BMI.
13
Another study on 597 cases
6
of primary anovulation and 1,695 controls showed that the risk of
Kilogr
anovulatory infertility is significantly raised in women with a BMI >27.
4
A slightly increased risk is associated with being moderately
2
overweight, while the greatest risk is found in obese women with
PCOS.
1
More recently, a third study on 3,029 subfertile ovulatory
0
patients found a lower fecundability in women with a BMI
Yes No
≥29kg/m
2
.
Exercise
In this trial, the occurrence of ovulation was assessed using a basal
body temperature (BBT) chart and either the measurement of plasma
Table 1: Association Between Body Mass Index and
progesterone or sonographic monitoring of the cycle.
14
Time to Pregnancy
16
Time to Pregnancy in Women with Proven Fertility BMI (kg/m
2
) Time to Pregnancy (FOR)
Significantly longer time to pregnancy has been found in English
18.5–24.9 1
women with a BMI
25.0–29.9 0.84 (0.77–0.92)
≥25kg/m
2
15
and in a similar retrospective cohort
of 7,327 US women (see Table 1). A third research group interviewed
≥30 0.72 (0.63–0.83)
2,374 couples 18 months after delivery, showing similar results and
FOR = fecundability odds ratio; BMI = body mass index.
also the negative effect on fecundity of obesity in the male partner.
Table 2: Fecundability in Women According to
The study concluded that if both of the partners are obese, the couple
Bodyweight and Polycystic Ovary Syndrome Symptoms
19
has a high risk of being subfecund.
17
Co-variates FR (95% CI) p-value
Longitudinal and Cohort Studies
BMI
A longitudinal study of 12,073 young US adults recently showed a
18.5–24.9 kg/m
2
(ref.) 1.00
significant reduction of fecundity associated with female (relative risk
25.0–29.9 kg/m
2
0.95 (0.83–1.10) 0.51
[RR] 0.69, 95% confidence interval [CI] 0.61–0.78) and male obesity (RR
≥30.0 kg/m
2
0.71 (0.57–0.87) 0.001
0.75, 95% CI 0.66–0.84).
18
PCOS Symptoms
No 1.00
A cross-sectional study on natural fecundity has recently been carried Yes 0.80 (0.70–0.92) 0.001
out in Northern Finland on a cohort of 5,889 women.
19
Obese women
FR = fertility ratio (the probability of conception within 12 months and 95% confidence
or patients with PCOS symptoms showed a decreased fecundability
interval [CI]); BMI = body mass index; PCOS = polycystic ovary syndrome.
and women presenting with both conditions had the lowest chance of
Figure 2: The Effect of Age and Being Overweight on
conceiving (RR 0.33, 95% CI 0.16–0.68). Table 2 reports the
Clinical Pregnancy Rates
fecundability of 1,727 women with self reported oligo-amenorrhoea
and/or hirsutism.
90
) 20 years
% 80
35 years
Lower Success Rate with Pro-fertility
ate ( 70
Treatments in Obese Women 60
Clomifene Citrate 50
Clomifene citrate (CC) is still the first-line treatment for the chronic 40
anovulation found in many overweight and PCOS patients, and a 36%
30
pregnancy rate is associated with its use. In obese women, the
Clinical pregnancy r
20
failure to induce ovulation (CC failure) is more frequent than in
10
normal-weight patients.
20
0
18 20 22 24 26 28 30 32 34 36 38 40
BMI
Metformin
Regression lines for clinical pregnancy rates as a function of body mass index (BMI) and age.
30
Despite its modest success rate when used alone, metformin may be
a useful co-treatment for CC-resistant obese patients.
21
The general anovulatory infertility. When used in obese women it is associated
use of CC and metformin is not superior to CC alone.
22
with a higher rate of cancellation and a reduced ovulation rate.
23
Low-dose Follicle-stimulating Hormone Laparoscopic Ovarian Drilling
The goal of low-dose follicle-stimulating hormone (FSH) therapy In the majority of PCOS anovulatory women, the reduction of ovarian
is the growth of a single follicle, and this method of induction of mass restores ovulation, but, again, the presence of excess weight
ovulation is widely used as first- or second-line treatment for decreases success rates.
24
EUROPEAN OBSTETRICS & GYNAECOLOGY 33
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