Our study illustrates how challenging it is to recruit women in the general population for PCC consultations in primary care. We measured the effect of the four-pronged outreach strategy in different ways. Firstly, regarding the uptake, the outreach resulted in a considerable number of applications for PCC (n = 587). To date, this is the largest preconception cohort recruited in primary care in the Netherlands. Most of the applications were a result of the large-scale mailing of letters targeting all women between 18 and 41 years. In relation to the reach of the outreach strategy, the effect seems small, but this is to be expected since the majority of these women would not actually consider becoming pregnant within the course of the study. We also found that the effect was mainly seen during a brief period of time following the mailing. Lastly, regarding the characteristics of women who applied for PCC, the strategy seems to have affected a diverse group of women. We reached a general population that aimed to conceive, as well as a subgroup of women with prior adverse pregnancy outcomes. Although more women with a higher educational attainment were recruited, the outreach strategy led to women with different socioeconomic backgrounds and different motivations applying for a PCC consultation.
Comparison to previous findings
Prior to the study, uptake of PCC consultations offered by GPs and midwives was low . In the absence of other outreach strategies, the consultations registered in our study can be attributed predominantly to the intervention. In other words, our outreach intervention resulted in a considerable increase of PCC delivery. The need for proactive outreach in order to educate about PCC services has also been illustrated by the low awareness regarding preconception health and PCC that has been found in previous studies [12, 22,23,24]. Combining PCC outreach or recruitment strategies, such as in our intervention, has been suggested before to improve delivery of PCC both in daily practice as well as in PCC studies [10, 25].
To our knowledge, a combination of the four outreach approaches in our strategy has not been evaluated before. However, some of the approaches have been implemented similarly before. Previous implementation of mailings about PCC from municipalities and GPs has also demonstrated a positive effect on uptake of PCC [18, 19]. One of these studies is in outline comparable to our approach of sending letters by GPs, but led to about 2.2% of the invited women attending PCC in contrast to 0.4% in our study . Possibly, women in our study underreported this approach due to overlap with the municipal letters. Other studies have also recommended our other two approaches of integrating PCC in child healthcare and peer education before [20, 21, 25,26,27]. Regarding the effect of the different outreach or recruitment approaches, Velott, Baker, Hillemeier, Weisman  have provided an overview of previous studies involving various types of health promotion. They indicate that there is not a single “best” method, but differentiate between active (or personal), and passive methods. Passive approaches such as mass mailings have the advantage of recruiting larger numbers of participants in absolute terms, as seen in our study as well. However, active approaches have the advantage of being able to give further information to the target population . In our study, active approaches such as peer education hardly resulted in any PCC applications, but might in itself already have fulfilled part of the purpose of PCC by educating women about preconception health.
Besides the predefined components of our outreach strategy, about 17% of the women in our study reported that other factors triggered them to apply for PCC. The most mentioned factor was information from their GP or midwife. This could indicate that raised awareness of healthcare professionals improves uptake of PCC. Furthermore, this is in line with prior findings that women like to be informed about PCC by a (primary) healthcare professional [24, 28, 29]. Opportunistic outreach by healthcare professionals during routine visits of clients may be complementary to the studied outreach strategy and valuable in reaching individuals with known risk factors, but on its own it does not guarantee reaching everyone.
In literature, it is often mentioned that reaching women who do not perceive a need for PCC (despite their risks) and who do not prepare for pregnancy is challenging [12, 30]. Our outreach intervention entailed a general approach since PCC is considered relevant for all women who consider getting pregnant . We applied Andersen’s model of healthcare utilization to reflect upon factors that likely influence application for PCC (see Additional file 1). This shows that the PCC services mainly reached women with good preconception health knowledge and a positive attitude towards PCC. Two main reasons for utilizing PCC were optimizing chances for a healthy pregnancy and fertility concerns. It has been proposed to integrate fertility concerns into PCC to meet the needs of women . With respect to the objective need for PCC, our cohort included women with social, obstetric or behavioral risk factors.
Study strengths and limitations
Applying different outreach approaches for PCC simultaneously was a key attribute of the study and has not been performed at this scale in the Netherlands before. The four-pronged strategy was implemented and evaluated in a real-time setting of different municipalities. This provided the opportunity to create awareness on the importance of perinatal health and promote PCC in these communities via existing stakeholders across medical and social domains .
At the same time, this design brought about challenges as well. Context factors (e.g. local policies) led to variation in the implementation of the outreach strategy across municipalities. For instance, not all municipalities and GP practices sent letters, and the targeted population included some women outside the designated areas and age range (e.g. peer education sessions could be integrated in other meetings where older women were present as well). Adapting the intended intervention to suit local settings reduces fidelity and completeness of the implementation . Understanding these mechanisms is important when evaluating effectiveness and qualitative analyses will be pursued to further explore the effect of the intervention.
There were a few limitations in the analysis of PCC uptake. We relied on participating practices to register appointments and respective outreach approaches, which was susceptible to unreliable registration. We did not have information about possible PCC consultations at non-participating practices and the outreach approach was not reported in 9 % of the appointments. In addition, we measured uptake for a brief, limited and varying period in each municipality. We believe we captured most of the effect, as we demonstrated that the effect faded out within the study period. Nevertheless, we only captured the effect of the outreach strategy in terms of uptake of PCC consultations and were not able to measure possible direct effects in terms of improved awareness or lifestyle changes regarding behavioral risks. For instance, the outreach approaches might have triggered women to look for more information without applying for a PCC consultation.
To reflect upon the population that utilized the PCC services, we relied on the cohort study . However, the participation rate in this cohort study was low (44%). Consequently, data might have been susceptible to selection bias. Data considering behavioral risk factors could have been influenced by the timing of filling in the questionnaire in relation to the actual PCC consultation. Half of the participants filled in the questionnaires after the consultation. This would most likely have resulted in underreporting of behavioral risks. Ideally, this study would have been able to compare characteristics of women who applied for PCC after outreach compared to characteristics of women who did not respond to the outreach. However, as the mailing was sent to all women 18–41 years, the Medical Ethical Committee deemed a non-response study too intrusive and inappropriate.