Impact of Caesarean section on subsequent fertility: a systematic review and meta-analysis.

STUDY QUESTION: Is there an association between a Caesarean section and subsequent fertility? SUMMARY ANSWER: Most studies report that fertility is reduced after Caesarean section compared with vaginal delivery. However, studies with a more robust design show smaller effects and it is uncertain whether the association is causal. WHAT IS KNOWN ALREADY: A previous systematic review published in 1996 summarizing six studies including 85 728 women suggested that Caesarean section reduces subsequent fertility. The included studies suffer from severe methodological limitations. STUDY DESIGN, SIZE, DURATION: Systematic review and meta-analysis of cohort studies comparing subsequent reproductive outcomes of women who had a Caesarean section with those who delivered vaginally. PARTICIPANTS/MATERIALS, SETTING, METHODS: Searches of Cochrane Library, Medline, Embase, CINAHL Plus and Maternity and Infant Care databases were conducted in December 2011 to identify randomized and non-randomized studies that compared the subsequent fertility outcomes after a Caesarean section and after a vaginal delivery. Eighteen cohort studies including 591 850 women matched the inclusion criteria. Risk of bias was assessed by the Newcastle-Ottawa scale (NOS). Data extraction was done independently by two reviewers. The meta-analysis was based on a random-effects model. Subgroup analyses were performed to assess whether the estimated effect was influenced by parity, risk adjustment, maternal choice, cohort period, and study quality and size. MAIN RESULTS AND THE ROLE OF CHANCE: The impact of Caesarean section on subsequent pregnancies could be analysed in 10 studies and on subsequent births in 16 studies. A meta-analysis suggests that patients who had undergone a Caesarean section had a 9% lower subsequent pregnancy rate [risk ratio (RR) 0.91, 95% confidence interval (CI) (0.87, 0.95)] and 11% lower birth rate [RR 0.89, 95% CI (0.87, 0.92)], compared with patients who had delivered vaginally. Studies that controlled for maternal age or specifically analysed primary elective Caesarean section for breech delivery, and those that were least prone to bias according to the NOS reported smaller effects. LIMITATIONS, REASONS FOR CAUTION: There is significant variation in the design and methods of included studies. Residual bias in the adjusted results is likely as no study was able to control for a number of important maternal characteristics, such as a history of infertility or maternal obesity. WIDER IMPLICATIONS OF THE FINDINGS: Further research is needed to reduce the impact of selection bias by indication through creating more comparable patient groups and applying risk adjustment

A population-based cohort study of the effect of Caesarean section on subsequent fertility

STUDY QUESTION Is there an association between Caesarean section and subsequent fertility? SUMMARY ANSWER There is no or only a slight effect of Caesarean section on future fertility. WHAT IS KNOWN ALREADY Previous studies have reported that delivery by a Caesarean section is associated with fewer subsequent pregnancies and longer inter-pregnancy intervals. The interpretation of these findings is difficult because of significant weaknesses in study designs and analytical methods, notably the potential effect of the indication for Caesarean section on subsequent delivery. STUDY DESIGN, SIZE, DURATION Retrospective cohort study of 1 047 644 first births to low-risk women using routinely collected, national administrative data of deliveries in English maternity units between 1 April 2000 and 31 March 2012. PARTICIPANTS/MATERIALS, SETTING, METHODS Primiparous women aged 15–40 years who had a singleton, term, live birth in the English National Health Service were included. Women with high-risk pregnancies involving placenta praevia, pre-eclampsia, eclampsia (gestational or pre-existing), hypertension or diabetes were excluded from the main analysis. Kaplan–Meier analyses and Cox proportional hazard models were used to assess the effect of mode of delivery on time to subsequent birth, adjusted for age, ethnicity, socio-economic deprivation and year of index delivery. MAIN RESULTS AND THE ROLE OF CHANCE Among low-risk primiparous women, 224 024 (21.4%) were delivered by Caesarean section. The Kaplan–Meier estimate of the subsequent birth rate at 10 years for the cohort was 74.7%. Compared with vaginal delivery, subsequent birth rates were marginally lower after elective Caesarean for breech (adjusted hazard ratio, HR 0.96, 95% CI 0.94–0.98). Larger effects were observed after elective Caesarean for other indications (adjusted HR 0.81, 95% CI 0.78–0.83), and emergency Caesarean (adjusted HR 0.91, 95% CI 0.90–0.93). The effect was smallest for elective Caesarean for breech, and this was not statistically significant in women younger than 30 years of age (adjusted HR 0.98, 95% CI 0.96–1.01). LIMITATIONS, REASONS FOR CAUTION We used birth cohorts from maternity units with good quality parity information. The data are likely to be nationally representative because the characteristics of the deliveries in included and omitted units were similar. There may be residual bias in our adjusted results due to unmeasured maternal factors such as obesity and voluntary absence of conception. Any residual bias would lead to an overestimate of the effect of Caesarean section on fertility, and the true effect is therefore likely to be smaller than the effect reported in our study. WIDER IMPLICATIONS OF THE FINDINGS Our results provide strong evidence that there is no or only a slight effect of Caesarean section on future fertility. The clinical and social circumstances leading to the Caesarean section have a greater effect on future fertility than the Caesarean section itself. This finding is important in light of rising Caesarean section rates. STUDY FUNDING/COMPETING INTEREST(S) IG-U is supported by the Lindsay Stewart R&D Centre, Royal College of Obstetricians and Gynaecologists, UK. The authors have no conflicts of interest to declare. TRIAL REGISTRATION NUMBER n/a

Wh-questions in agrammatism: A movement deficit?

Agrammatic Broca patients suffer from a language deficit related to syntactic movement. These patients have difficulties producing and comprehending sentences derived through syntactic movement. However, patients’ performance on wh-questions shows an intriguing pattern. These constructions involve movement of the wh-word. Still, patients’ comprehension of wh-questions seems to be intact, whereas their production is severely impaired. This raises the question whether the operation of wh-movement is only impaired in patients’ production and does not affect patients’ comprehension. This question is examined in several experiments on French-speaking Broca patients. French allows the wh-word either to remain in its base position or to move. Therefore, French forms a unique environment to examine the effect of wh-movement. The results show that wh-movement affects both the production and comprehension abilities of Broca patients. These results are discussed in light of therapy studies on wh-questions in Broca’s aphasia

Photodissociation of the OD radical at 226 and 243 nm

The photodissociation dynamics of state selected OD radicals has been examined at 243 and 226 nm using velocity map imaging to probe the angle–speed distributions of theD(2S) and O(3P2) products. Both experiment and complementary first principle calculations demonstrate that photodissociation occurs by promotion of OD from high vibrational levels of the ground X 2Π state to the repulsive 1 2Σ− state

Simulations of Cold Electroweak Baryogenesis: Finite time quenches

The electroweak symmetry breaking transition may supply the appropriate out-of-equilibrium conditions for baryogenesis if it is triggered sufficiently fast. This can happen at the end of low-scale inflation, prompting baryogenesis to occur during tachyonic preheating of the Universe, when the potential energy of the inflaton is transfered into Standard Model particles. With the proper amount of CP-violation present, the observed baryon number asymmetry can be reproduced. Within this framework of Cold Electroweak Baryogenesis, we study the dependence of the generated baryon asymmetry on the speed of the quenching transition. We find that there is a separation between ``fast'' and ``slow'' quenches, which can be used to put bounds on the allowed Higgs-inflaton coupling. We also clarify the strong Higgs mass dependence of the asymmetry reported in a companion paper (hep-ph/0604263).Comment: 18 pages, 20 figure

Insight into the neurophysiological processes of melodically intoned language with functional MRI

Background: Melodic Intonation Therapy (MIT) uses the melodic elements of speech to improve language production in severe nonfluent aphasia. A crucial element of MIT is the melodically intoned auditory input: the patient listens to the therapist singing a target utterance. Such input of melodically intoned language facilitates production, whereas auditory input of spoken language does not. Methods: Using a sparse sampling fMRI sequence, we examined the differential auditory processing of spoken and melodically intoned language. Nineteen right-handed healthy volunteers performed an auditory lexical decision task in an event related design consisting of spoken and melodically intoned meaningful and meaningless items. The control conditions consisted of neutral utterances, either melodically intoned or spoken. Results: Irrespective of whether the items were normally spoken or melodically intoned, meaningful items showed greater activation in the supramarginal gyrus and inferior parietal lobule, predominantly in the left hemisphere. Melodically intoned language activated both temporal lobes rather symmetrically, as well as the right frontal lobe cortices, indicating that these regions are engaged in the acoustic complexity of melodically intoned stimuli. Compared to spoken language, melodically intoned language activated sensory motor regions and articulatory language networks in the left hemisphere, but only when meaningful language was used. Discussion: Our results suggest that the facilitatory effect of MIT may - in part - depend on an auditory input which combines melody and meaning. Conclusion: Combined melody and meaning provide a sound basis for the further investigation of melodic language processing in aphasic patients, and eventually the neurophysiological processes underlying MIT. Compared to spoken language, melodically intoned language activated sensory motor regions and articulatory language networks in the left hemisphere, but only when meaningful language was used. Our results suggest that the facilitatory effect of MIT may - in part - depend on an auditory input which combines melody and meaning. As such, they provide a sound basis for further investigation of melodic language processing in aphasic patients, and eventually the neurophysiological processes underlying MIT