Starting at the Beginning
Several lifestyle factors have been identified which can promote optimal fertility, including dietary behaviors, stress management, and maintenance of a healthy weight. In addition, adequate nutrient status can influence not only the ability to get pregnant, but the health of the egg and sperm, and thus the health of the child born to those parents. The following interventions can greatly influence fertility, and it is recommended that all couples trying to conceive consider these interventions, whether they have trouble with fertility or not.
Obesity poses a significant threat to fertility as well as for the offspring born to obese parents. In obese men, there is increased aromatase activity, which irreversibly converts testosterone to estradiol resulting in decreased testosterone and increased estrogen levels.[i] It is likely that this plays a role in the lower sperm counts, lower sperm concentration, and poor sperm morphology seen in men with increased BMI and central adiposity. Obese men also have fewer motile sperm and lower testosterone levels, as mentioned above.[ii][iii]
It’s not only men who experience decreased fertility as their weight creeps up; women are also affected. Obese women have lower pregnancy rates (20.8% versus 28.3% successful cycles, p=0.04) when they undergo IVF and obese women are more likely to experience preterm births after IVF. [iv] [v] [vi] Although this study represents women undergoing IVF, similar fertility trends exist in women trying to conceive naturally. [vii] Together, obese couples experience higher rates of miscarriage in both spontaneous conception as well as assisted reproduction.[viii] In addition to the hormonal changes noted for men, this decrease fertility may be due to increased levels of inflammation which affect ovarian response and the uterine/endometrial environment.
Obesity poses such a hinderance to fecundity that many fertility clinics place a BMI limit for candidacy for the procedure. Addressing obesity for patients is essential to support a healthy conception and pregnancy, and maintenance of a healthy weight should be a first goal for couples wishing to get pregnant. If a weight loss plan is implemented, it is strongly recommended that clinicians consider promoting a modified Mediterranean diet, as this diet also has fertility-promoting effects.
[i] Cohen, PG. Obesity in men: the hypogonadal-estrogen receptor relationship and its effects on glucose homeostasis. Med Hypotheses. 2008;70(2):358-60.
[ii] Sermondade N, Faure C, Fezeu L et al. Obesity and increased risk for oligozoospermia and azoospermia. Arch Intern Med. 2012;172(5):440-2.
[iii] Hakonsen LB, Thulstrup AM, Aggerholm AS et al. Does weight loss improve semen quality and reproductive hormones? Results from a cohort study of severely obese men. Reprod Health. 2011 Aug 17;8-24.
[iv] Pinborg A, Gaarsley C, Hougaard CO et al. Influence of female bodyweight on IVF outcome: a longitudinal multicentre cohort study of 487 infertile couples. Reprod Biomed Online. 2011 Oct;23(4):490-9.
[v] Kumbak B, Oral E, Bukulmez O. Female obesity and assisted reproductive technologies. Semin Reprod Med. 2012 Dec;30(6):507-16.
[vi] Dickey RP, Xiong X, Gee RE et al. Effect of maternal height and weight on risk of preterm birth in singleton and twin births resulting from in vitro fertilization: a respective cohort study using the Society for Assisted Reproductive Technology Clinic Outcome Reporting System. Fertil Steril. 2012;97(2):349-54.
[vii] Cardozo ER, Neff LM, Brocks ME, et al. Infertility patients’ knowlede of the effects of obesity on reproductive health outcomes. Am J Obstet Gynecol. 2012 Dec;207(6):509.
[viii] Boots C, Stephenson MD. Does obesity increase the risk of miscarriage in spontaneous conception: a systematic review. Semin Reprod Med. 2011;29(6):507-13.