Louisa Brown, the first child conceived in vitro, was born 45 years ago. At that time, a successful in vitro fertilisation (IVF) was a sensation, now assisted reproductive technologies (ARTs), such as IVF and intracytoplasmic sperm injection (ICSI), are established methods in the treatment of infertility and helped millions of involuntarily childless couples (Chang et al., Reference Chang, Hwu, Chen, Hou and Cheng2020; Wyns et al., Reference Wyns, de Geyter, Calhaz-Jorge, Kupka, Motrenko, Smeenk, Bergh, Tandler-Schneider, Rugescu, Vidakovic and Goossens2017). Nevertheless, this technique is still discussed as a risk factor for preterm birth, foetal growth restriction, and several obstetric problems (Berntsen et al Reference Berntsen, Söderström-Anttila, Wennerholm, Laivuori, Loft, Oldereid, Romundstad, Bergh and Pinborg2019; Helmerhorst et al., Reference Helmerhorst, Perquin, Donker and Keirse2004; Koudstaal et al., Reference Koudstaal, Braat, Bruinse, Naaktgeboren, Vermeiden and Visser2000; Malchau et al., Reference Malchau, Loft, Henningsen, Nyboe Andersen and Pinborg2014; Pandey et al., Reference Pandey, Shetty, Hamilton, Bhattacharya and Maheshwari2012; Zadori et al., Reference Zádori, Kozinszky, Orvos, Katona, Pál and Kovács2003). It is still unclear whether these problems are directly related to ART use (Romundstad et al., Reference Romundstad, Romundstad, Sunde, von Düring, Skjaerven, Gunnell and Vatten2008; Stern et al., Reference Stern, Luke, Tobias, Gopal, Hornstein and Diop2015; Valenzuela-Alcaraz et al., Reference Valenzuela-Alcaraz, Crispi, Manau, Cruz-Lemini, Borras, Balasch and Gratacós2016), because these adverse effects are mainly associated with multiple pregnancies, which are more common after ART treatment. A typical obstetric problem associated with ART is breech presentation (Noli et al., Reference Noli, Baini, Parazzini, Mauri, Vignali, Gerli, Favilli and Cipriani2019; Romundstad et al., Reference Romundstad, Romundstad, Sunde, von Düring, Skjærven and Vatten2009; Schieve et al., Reference Schieve, Cohen, Nannini, Ferre, Reynolds, Zhang, Jeng, Macaluso and Wright2007; Slavov, Reference Slavov2021). Two recently published studies characterised by huge sample sizes (Chen et al., Reference Chen, Hunt, Palmer, Bull and Callander2023; Londero et al., Reference Londero, Massarotti, Xholli, Fruscalzo and Cagnacci2023) revealed a significant association between ART and breech presentation. In previous studies, however, it was discussed whether ART is truly an independent risk factor for breech presentation or whether factors such as older maternal age, nulliparity, or preterm birth, which are typical of ART pregnancies, might increase the risk for breech presentation independent of ART (Romundstad et al., Reference Romundstad, Romundstad, Sunde, von Düring, Skjærven and Vatten2009). Therefore, we tested the hypothesis: ART is not an independent risk factor for the increased prevalence of breech presentation among singleton term births, but ART-associated factors such as higher maternal age, nulliparity, and gestational week increase the risk of breech presentation.

In this single-centre and medical record-based study, we analysed the association patterns between the mode of conception and child presentation among 11920 singleton term births (>37 weeks of gestation) taking place between 2010 and 2020 at the Donaustadt Clinic in Vienna, Austria. We hypothesise that child presentation among singleton term births is not associated with the conception mode.

Our dataset included information regarding the conception mode (spontaneous or assisted (IVF or ICSI)), maternal age, height, prepregnancy weight status, gestational weight gain, smoking, number of previous births, caesarean section, and newborn sex and size (birth weight, birth length, and head circumference). Data analysis was carried out using SPSS version 27.0. (IBM, Austria). To test group differences, t-tests were computed. For categorical variables, χ² tests were applied. To evaluate the association of child presentation and conception mode, logistic regression was performed.

Three hundred twenty-six mothers (2.7%) conceived via either ICSI or IVF. Five hundred twenty-seven children (4.4%) were delivered in breech presentation. Table 1 demonstrates significant differences between ART and spontaneously conceived pregnancies. Mothers pregnant via ART were significantly older, taller, and heavier before pregnancy. Spontaneously conceiving mothers had experienced significantly more births and were more likely to be smokers. ART was significantly positively associated with a shorter pregnancy, although only term births have been included, an increased cesarean section rate, and more female offspring. No significant differences in newborn size apart from head circumference could be observed. ART increased the crude risk of breech presentation significantly (OR = 1.67; 95% CI 1.71 – 2.38). At first glimpse, these results plead for an independent positive association between ART and breech presentation. After adjusting for maternal age, height, parity, smoking, newborn weight, gestational week, and newborn sex, ART had no longer a significant impact on the risk of breech presentation. The logistic regression indicates a significantly positive association between breech presentation and maternal age, maternal height, birthweight, gestational week as well as the number of previous births, but not with ART (Table 2). Consequently, our hypothesis was corroborated by our results. Our results partly follow those of several other studies (Berntsen et al., Reference Berntsen, Söderström-Anttila, Wennerholm, Laivuori, Loft, Oldereid, Romundstad, Bergh and Pinborg2019; Helmerhorst et al., Reference Helmerhorst, Perquin, Donker and Keirse2004; Koudstaal et al., Reference Koudstaal, Braat, Bruinse, Naaktgeboren, Vermeiden and Visser2000; Malchau et al., Reference Malchau, Loft, Henningsen, Nyboe Andersen and Pinborg2014; Pandey et al., Reference Pandey, Shetty, Hamilton, Bhattacharya and Maheshwari2012; Slavov, Reference Slavov2021; Wyns et al., Reference Wyns, de Geyter, Calhaz-Jorge, Kupka, Motrenko, Smeenk, Bergh, Tandler-Schneider, Rugescu, Vidakovic and Goossens2017; Zadori et al., Reference Zádori, Kozinszky, Orvos, Katona, Pál and Kovács2003) but contrast with the recently published studies by Chen et al. (Reference Chen, Hunt, Palmer, Bull and Callander2023) and Londero et al. (Reference Londero, Massarotti, Xholli, Fruscalzo and Cagnacci2023). In our study, the increased rates of breech presentation in ART-conceived newborns cannot solely be explained by ART treatment itself. While older maternal age increased the risk of breech presentation significantly, a higher number of previous births (OR = 0.84) and a higher gestational week – even among term births – (OR = 0.60) led to the greatest decrease in the risk of breech presentation.

Table 1. Maternal and Newborn Characteristics among Term Births According to Conception (Spontaneous versus Assisted Conception)

To test group differences, t-tests were computed. For categorical variables, χ² tests were applied.

We are aware that our sample size is tiny in comparison with those of Chen et al. (Reference Chen, Hunt, Palmer, Bull and Callander2023) and Londero et al. (Reference Londero, Massarotti, Xholli, Fruscalzo and Cagnacci2023), and that this fact is a major limitation of our study. Nevertheless, we could verify our hypothesis. For our sample, the higher rates of breech presentation among IVF and ICSI pregnancies may not be due to the ART treatment alone but might be due to the mostly higher maternal age, the lower parity, and shorter pregnancy among women suffering from infertility (Table 2).

Table 2. The Associations Between Birth Presentation and Maternal as well as Newborn Parameters among Singleton Term Births

Logistic regression analysis.