Archives of Gynecology and Obstetrics https://doi.org/10.1007/s00404-017-4605-4 MATERNAL-FETAL MEDICINE Changes in birth‑related pain perception impact of neurobiological and psycho‑social factors Sebastian Berlit1 · Stefanie Lis2 · Katharina Häfner3 · Nikolaus Kleindienst3 · Ulf Baumgärtner4 · Rolf‑Detlef Treede4 · Marc Sütterlin1 · Christian Schmahl3,5 Received: 9 October 2017 / Accepted: 21 November 2017 © Springer-Verlag GmbH Germany, part of Springer Nature 2017 Abstract Purpose To analyse post-partum short- and long-term pain sensitivity and the infuence of endogenous pain inhibition as well as distinct psycho-social factors on birth-related pain. Methods Pain sensitivity was assessed in 91 primiparous women at three times: 2–6 weeks before, one to 3 days as well as ten to 14 weeks after childbirth. Application of a pressure algometer in combination with a cold pressor test was utilised for measurement of pain sensitivity and assessment of conditioned pain modulation (CPM). Selected psycho-social factors (anxiety, social support, history of abuse, chronic pain and fear of childbirth) were evaluated with standardised questionnaires and their efect on pain processing then analysed. Results Pressure pain threshold, cold pain threshold and cold pain tolerance increased signifcantly directly after birth (all p < 0.001). While cold pain parameters partly recovered on follow-up, pressure pain threshold remained increased above baseline (p < 0.001). These pain-modulating efects were not found for women with history of abuse. While CPM was not afected by birth, its extent correlated signifcantly (r = 0.367) with the drop in pain sensitivity following birth. Moreover, high trait anxiety predicted an attenuated reduction in pain sensitivity (r = 0.357), while there was no correlation with fear of childbirth, chronic pain and social support. Conclusion Pain sensitivity showed a decrease when comparing post-partum with prepartum values. The extent and direc- tion of CPM appear to be a trait variable that predicted post-partum hypalgesia without being changed itself. Post-partum hypalgesia was reduced in women with a history of abuse and high trait anxiety, which suggests that individual diferences in CPM afect childbirth experience. Keywords Birth · Pain · Social support · Abuse · Anxiety · Fear of childbirth Introduction can lead to pathological antepartum as well as post-partum efects. Birth pain considerably infuences fear of child- Giving birth is arguably one of the most emotionally intense birth, which in turn is known to have a predominant impact and relevant key events in women’s life. Besides positive on the continuously rising caesarean section rate in the connotations, the substantial pain experienced under labour Western world [1]. Moreover, excessive labour pain can be experienced as a traumatic event which may lead to pro- Sebastian Berlit, Stefanie Lis, Rolf-Detlef Treede, Marc Sütterlin longed psychological sequelae [2]. These aspects explain and Christian Schmahl contributed equally. * Sebastian Berlit 3 Department of Psychosomatic Medicine and Psychotherapy, [email protected] Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany 1 Department of Obstetrics and Gynaecology, University 4 Department of Neurophysiology, Centre of Biomedicine Medical Centre Mannheim, Heidelberg University, and Medical Technology Mannheim, Medical Faculty Theodor‑Kutzer‑Ufer 1‑3, 68167 Mannheim, Germany Mannheim, Heidelberg University, Mannheim, Germany 2 Institute of Psychiatric and Psychosomatic Psychotherapy, 5 Department of Psychiatry, Schulich School of Medicine Central Institute of Mental Health, Medical Faculty and Dentistry, Western University, London, ON, Canada Mannheim, Heidelberg University, Heidelberg, Germany Vol.:(0123456789)1 3 Archives of Gynecology and Obstetrics the importance of research on labour pain, which has been of painful stimuli such as a dolorimeter or the cold pressor addressed by various authors [3–10]. test (CPT) [4, 5, 12, 20]. Furthermore, most investigations Besides the disadvantageous psychological efects, birth in this context focused on particular labour pain infuencing pain is assumed to sustainably change physiological patterns factors [3]. of pain perception, i.e. to result in a reduced pain sensitiv- As labour pain can be afected by multiple physiologi- ity, which even persists after birth [4, 7]. Studies identifed cal, social and psychological determinants, we designed both biological and psycho-social factors as determinants this prospective investigation to assess short- and long-term of this change: alterations of pain processing after birth and the infuence of One of the biological mechanisms is endogenous pain multiple factors, which previously have been shown to have inhibition. First described in men severely wounded in battle an impact on birth pain. Incorporating the potentially bias- many studies have confrmed the existence of a descending ing neurobiological mechanism of CPM, we focused on the pain modulatory circuit that diminishes pain [11]. The status impact of the psycho-social determinants fear of childbirth, of this system can be evaluated by activation of pathways anxiety, social support and history of abuse on birth-related in the nociceptive system and quantitative sensory testing pain perception [3, 4, 6–9]. To our knowledge, this is the (QST) [12]: conditioned pain modulation (CPM) can be frst investigation with a comprehensive analysis of altera- used to measure the descending inhibition of nociceptive tions in pain processing after birth over time, which focuses signals indicated by the attenuation of the perceived inten- on both the efects of endogenous pain inhibition by means sity of a painful test stimulus after application of a painful of pressure pain sensitivity in the context of a CPM para- conditioning stimulus [13, 14]. It thus provides an objective digm and psycho-social factors. In line with the literature, measurement tool that allows to test whether and to which we hypothesised that giving birth will result in a reduced extent this mechanism contributes to both short- and long- pain sensitivity, indicated by increases in pain thresholds term reduction in post-partum pain sensitivity. to standardised painful stimuli. We expected that women’s Furthermore, some authors have confrmed that inter- endogenous pain inhibition before birth predicts the severity individual diferences in pain processing depend on a variety of change in pain perception after birth, with a stronger con- of psycho-social factors and this holds true for birth-related ditioned pain modulation being related to a stronger decrease pain processing: In a prospective investigation using a cold in pain sensitivity. Moreover, we hypothesised that psycho- pressure test to measure pain sensitivity, Saito et al. found social factors will afect birth-related alterations. Based on that patients with fear of childbirth tolerated pain signif- previous studies, we expected that both general anxiety and cantly shorter than did women without fear both during in fear of childbirth would attenuate the reduction in pain sen- the pregnancy and in the post-partum period [15]. Beyond sitivity after birth. fear specifcally related to giving birth, inter-individual dif- ferences in anxiety, as an individual’s stable personality fea- ture, seem to contribute to a variability of pain perception Methods changes during birth: Various studies revealed that increased anxiety is linked to augmented labour pain [3, 16–18]. More- Subjects over, the experience of social support and psycho-social factors such as a history of adverse childhood trauma may This investigation was approved by the Medical Ethics Com- infuence pain sensitivity after birth: a history of a traumatic mittee II of the University Medical Centre Mannheim, Hei- sexual experience increased pain sensitivity, leading to a delberg University, Mannheim, Germany (2010-347 N-MA) more traumatic birth experience in general [9, 19]. and conducted according to the Declaration of Helsinki as In sum, both psychological as well as biological factors well as the Declaration of the World Medical Association. are supposed to afect pain processing in the context of giv- After obtaining written informed consent, a total of 131 ing birth. However, most of the investigations so far focussed pregnant women registering for planned vaginal birth at the on pain processing only during or shortly after delivery using Department of Obstetrics of the University Medical Cen- solely single measurements. Studies capturing antepartum tre Mannheim were included in this prospective study. At pain processing and its changes following birth in longi- the time of recruitment, women were not in labour neither tudinal studies with repeated measurements over weeks or did they experience contractions nor did they have a his- months are sparse [4]. Thus, it is still unclear whether alter- tory of psychiatric illness. In order to be included in this ations of pain perception indeed persist over an extended investigation, patients had to be of legal age, right-handed period of time or not. Moreover, most studies focused on and primipara. In order to fulfl the criteria for follow-up alterations in the subjective perception of ongoing pain using assessment, women had to have given birth vaginally to a self-report questionnaires [3]. Only few authors investigated full-term singleton with cephalic presentation. Non-age, pain perception in response