title: Pain during embryo transfer is independently associated with clinical pregnancy in fresh/frozen assisted reproductive technology cycles.
abstract: OBJECTIVE
  To assess whether pain experienced during embryo transfer (ET) is associated with the chance of clinical pregnancy in assisted reproductive technology cycles.
  
  
  METHODS
  This was a prospective observational study of 284 women conducted between July 2011 and January 2014. Women under 40 years undergoing in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) cycles followed by fresh/frozen ET were recruited. Pain was measured using a 100-mm visual analogue scale. Several factors relating to both pain and also the nature of the ET procedure were recorded: use of vulsellum, uterine contractility, depth of ET, duration of ET catheter insertion, urgency of micturition, psychological profile tests, salivary α-amylase and salivary cortisol. Primary outcome was the achievement of clinical pregnancy.
  
  
  RESULTS
  Women who experienced pain during ET had a significantly lower clinical pregnancy rate compared with women who did not (42.2% vs 53.8%; P = 0.03). Non-pregnant women also had significantly higher pain scores compared with pregnant women (10.3 vs 6.4; P = 0.01). Pain was independent of >20 variables relating to (i) the nature of the ET procedure; (ii) psychological testing; and (iii) potential confounding factors inherent to IVF/ICSI. On binary logistic regression analysis, pain was an independent predictor for the chance of clinical pregnancy (OR, 0.59; 95%CI: 0.37-0.94; P = 0.03).
  
  
  CONCLUSIONS
  Pain during ET is independently associated with the chance of clinical pregnancy. The underlying mechanism could involve factors other than nature of the ET and the psychological state of the patient, and warrants further investigation.
authors.affiliation: Assisted Reproductive Technology Unit, Prince of Wales Hospital, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong.
authors.forename: Sotirios H
authors.initials: SH
authors.lastname: Saravelos
authors.affiliation: Assisted Reproductive Technology Unit, Prince of Wales Hospital, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong.
authors.forename: Alice Wy
authors.initials: AW
authors.lastname: Wong
authors.affiliation: Assisted Reproductive Technology Unit, Prince of Wales Hospital, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong.
authors.forename: Grace Ws
authors.initials: GW
authors.lastname: Kong
authors.affiliation: Assisted Reproductive Technology Unit, Prince of Wales Hospital, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong.
authors.forename: Jin
authors.initials: J
authors.lastname: Huang
authors.affiliation: Mailman School of Public Health, Columbia University Medical Centre, New York, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Klitzman
authors.affiliation: Assisted Reproductive Technology Unit, Prince of Wales Hospital, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong.
authors.forename: Tin-Chiu
authors.initials: TC
authors.lastname: Li
mesh_terms: D000328:Adult; D004624:Embryo Transfer / Q000009:adverse effects* / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D010146:Pain / Q000150:complications*; D010147:Pain Measurement; D058748:Pain Perception; D011247:Pregnancy; D018873:Pregnancy Rate; D011446:Prospective Studies; D012372:ROC Curve; D020554:Sperm Injections, Intracytoplasmic
keywords: assisted reproductive technology; embryo transfer; infertility