Postpone pregnancy until vitamin levels stabilise after bariatric surgery

Updated: Sep 17

Researchers from The Netherlands have recommended postponing pregnancy until vitamin levels stabilise, irrespective of the interval between surgery and pregnancy. The findings were reported in the paper, ‘The effects of bariatric surgery on periconception maternal health: a systematic review and meta-analysis’, published in the journal Human Reproductive Update, after they performed a systematic review and meta-analysis into the impact of bariatric surgery on women’s periconceptional health.

The aim of the review was to investigate associations between bariatric surgery and determinants of periconception maternal health such as endocrine changes, fertility, vitamin status, irregular menstrual cycles, miscarriages and congenital malformations. After carried out a literature review and excluding papers that did not meet the selection criteria, 51 papers were analysed.

The authors reported that before-after studies showed that hormonal serum levels normalised and menstrual cycles became more regular with an associated decrease in infertility and that there were no short-term risks for reproductive periconception outcomes such as the increased risk of miscarriages or congenital malformations. However, vitamin deficiencies occurred regularly after bariatric surgery. The meta-analysis showed that fertility and menstrual cycle regularity improved whereas there was no association between bariatric surgery and congenital malformations and miscarriage rate, respectively.


Overall, bariatric surgery has a positive effect on fertility, although the reason for fertility treatment was not specified in these articles and a comparison with women of the same BMI category as before bariatric surgery was not made. Most patients, who could not conceive spontaneously before bariatric surgery, had no difficulties after this surgery and the positive effect of bariatric surgery on sexual functioning could be an important factor. The authors found that weight loss, induced by bariatric surgery, was associated with the restoration of a regular menstrual cycle.

They noted that obesity is associated with disorders such as diabetes mellitus, which can affect fertility and endocrine homeostasis, however, it is unknown whether obesity and associated disorders aggravate each other or operate independently. Therefore, the authors recommended evaluating the individual effect of bariatric surgery on these outcomes and fertility.

Regarding conception, they advise women have non-oral contraceptives such as intra-uterine devices to postpone pregnancy, as vomiting and diarrhoea often occur after bariatric surgery, which influences the effectiveness of oral contraceptives.

“The take-home message is the need for worldwide, substantiated guidelines for post-bariatric patients regarding vitamin supplementation, before and during pregnancy. We recommend guidelines that enable a personalised approach, taking the length of the bypassed small intestines into account,” the authors stressed. “…Overall, independent of the type of bariatric surgery, post-surgical patients are vulnerable to develop both fat- and water-soluble vitamin deficiencies. We propose professional guidance by a multidisciplinary team with a gynaecologist or midwife, specialised dietitian, bariatric surgeon and internal medicine specialist.”

The researchers found no association between bariatric surgery and miscarriages or an increased risk for congenital malformations in offspring of women with bariatric surgery vs. women without preconception bariatric surgery.


They also added that the long-term consequences of bariatric surgery on fertility are still unknown and proposed longer follow-up in women of reproductive age before and after surgery, and recommended follow-up of their offspring along the entire life course.


“Bariatric surgery has proven to be effective in the achievement of weight reduction, but the risks of iatrogenic malnutrition can also influence foetal growth and development and offspring health, even though the effects may not be directly visible and are largely unknown,” they concluded. “Therefore, we advise extensive follow-up of both mother and her unborn offspring, from the preconception period onward, including regular assessment of maternal vitamin status, foetal growth and follow-up of the offspring.”


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