Probiotic therapy in couples with infertility: A systematic review.

The reproductive microbiome is becoming increasingly recognised for its influence on fertility. While there has been much work to investigate the treatment of bacterial vaginosis and disordered microbiomes in optimizing outcomes in Assisted Reproductive Technology (ART), the role of routinely prescribed probiotics is yet to be established. The therapeutic potential of probiotic therapy remains an exciting opportunity in ART and this review endeavours to summarise its evidence to date. A systematic review of MEDLINE (Pubmed), Allied Health Literature (CINAHL), EMBASE, Web of Science and the Cochrane database was performed on 7th May 2019, and repeated on 26th August 2019. The search was built using the terms 'subfertility;' 'probiotic therapy;' 'clinical pregnancy rate' and 'assisted reproductive outcomes.' The primary outcome was change in clinical pregnancy rate. Secondary outcomes included improvements in male and female fertility parameters and microbial assessment. The initial search found 882 articles, of which 26 full manuscripts were reviewed. Four articles were eligible for inclusion. Of the two studies that reported the primary outcome, only one study found probiotics increased the clinical pregnancy rate non-significantly (48.0%-58.8%, p = 0.47). It also found higher miscarriage rate (30 % vs 16.6 %, p = 0.47) in the group treated with probiotics. Both studies on males with oral probiotic found significantly improved sperm motility. While benefit in sperm motility has been observed with male probiotic therapy, there is conflicting evidence on the efficacy of probiotic therapy for women undergoing assisted reproduction. High quality randomized studies are needed to definitively examine probiotic therapy and establish its benefit for couples undergoing assisted reproduction.

Glucose, glycine and diglycine in test meals at stimuli to a duodenal osmoreceptor slowing gastric emptying.

1. Five subjects took 210 test meals of 750 ml. water containing 30--300 m-molal glucose or glycine, or 15--150 m-molal diglycine, or plain water. 2. The greater the concentration of solute, the greater was the volume of original meal recovered from the stomach after a fixed time. 3. On a molal basis glucose was half as effective as diglycine in slowing gastric emptying. This was consistent with the osmoreceptor being exposed to the diglycine after it had been split by the hydrolase of the cytosol of enterocytes (the absorbing cells of the small intestine). 4. The slowing of gastric emptying (ml./mole.1.) was about 10% greater for glycine than it was for glucose. There was apparently a threshold concentration below which glycine did not slow gastric emptying. 5. It was proposed that the response of the doudenal osmoreceptor might depend upon shrinking and swelling of the lateral intercellular space around the enterocytes.

Actions of glucose and potassium chloride on osmoreceptors slowing gastric emptying.

1. Five subjects were given 373 test meals of 750 ml. water containing a range of concentrations of glucose or potassium chloride.2. The greater the concentration of solute in the meals, the greater was the volume of the test meal recovered from the stomach after a fixed time.3. When the concentrations of the solutes were expressed as m-osmole/l. corrected by osmotic coefficients based on vapour pressures at 37 degrees C, glucose and potassium chloride were indistinguishable in slowing gastric emptying.4. These results are consistent with the regulation of gastric emptying by a duodenal receptor responding to osmotic pressure.5. Potassium chloride was more nauseating than glucose on an osmolar basis.