Introduction

A multiple pregnancy is when a gestation results in multiple foetuses [1]. Multiple births have been increasing since the 1980s, with the rate in England and Wales having increased from 9.8 per 1000 of all maternities in 1980 to 14.4 per 1000 in 2020 [2]. Factors including an increased use of assisted conception, a trend to having children later in life and a higher survival rate of premature babies may contribute to this increase [3].

Multiple births are regarded as high risk with a higher likelihood of obstetric complications and poorer mental health compared to singleton births [1]. For example, women with multiple pregnancies were more likely to have caesarean birth even though vaginal birth was planned [4,5], preterm birth [6], and babies with low birthweight [7,8]. Additionally, they had worse postnatal mental health outcomes compared to those with singleton births [9]. They were less likely to breastfeed [10] which may be due to the physical challenges of caring for and feeding more than one baby [11], or also be a result of a perception that breastmilk alone was not enough to sustain the nutritional requirements of twins [12]. Despite the additional support needed for breastfeeding in multiple births, very few studies on breastfeeding interventions included women with multiple births [13].

The high-risk nature of multiple pregnancies was compounded by COVID-19, creating additional challenges. For example, a study in India found that COVID- 19 infection and multiple pregnancies increased women’s risk of preterm birth compared to singleton pregnancies [14]. Women who tested COVID-19 positive or were symptomatic were recommended to breastfeed by the World Health Organisation (WHO) while taking standard COVID precautions such as wearing a mask and hand washing or, in the case of severe illness, expressing milk for feeding [15]. However, Jonsdottir et al’s [16] research conducted in 2020−21 found that compared to twins born at term, parents of late preterm twins faced distinctive challenges which increased the likelihood of breastfeeding cessation after one month postpartum. Lack of access to support via social networks and health services had negative impact on both breastfeeding practices and maternal mental health during COVID-19 [17]. With more than one baby to feed and look after simultaneously, lack of access to social and health provider support due to COVID-19 could negatively affect those with multiple births more than singleton births.

Considering the vulnerability of families with multiple births and the adverse impact COVID-19 has on the perinatal outcomes, research during COVID-19 is needed to inform practices to support this group and prepare for future pandemics. Our study aimed to establish the factors, including infant feeding practices, support, and obstetric factors, associated with multiple births and to address the gap that no such research had been conducted during the pandemic in the United Kingdom (UK).

Methods

Results

Of 877 postnatal women who filled in the survey, 858 were eligible, with 805 (93.8%) having singleton births and 53 (6.2%) having multiple births. More than 50% of participants with singleton or multiple births were between 30−39 years old, had an undergraduate or higher degree, were married, lived in urban areas, were white ethnicity, and were multiparous. In addition, the majority reported that they had not tested COVID-19 positive, and had at least one doze of COVID-19 vaccine, and were somewhat or very worried about getting infected with the coronavirus, but did not experience any impact of COVID-19 on food insecurity (Table 1). Bivariate analysis revealed that socio-demographic factors and COVID-19 related factors were not associated, while obstetric factors such as preterm birth, NICU admission, birthweight, mode of birth, and postnatal depression were statistically significantly associated with multiple births (Table 1).

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Table 1. Association between singleton/multiple births and socio-demographic, obstetric and COVID-19 related factors.

https://doi.org/10.1371/journal.pone.0352340.t001

Regarding infant feeding practices (Table 2), approximately 97% of participants who had singleton or multiple births planned to breastfeed during pregnancy, but 85.4% of them reported breastfeeding in the previous 24 hours, and some also reported providing infant formula (24.8%), expressed human milk (17.6%), or complementary foods (10.5%). Bivariate analysis showed that those who had singleton births were more likely to report breastfeeding their infants directly from breast in the previous 24 hours (p < 0.05), whereas those with multiple births were more likely to report feeding their infants with expressed breast milk or infant formula (p < 0.01). In addition, the impact of COVID-19 on baby fed directly from breast was not associated with multiple births, but those who had multiple births were more likely to report that COVID-19 shortened or lengthened the duration of feeding expressed breast milk compared to those with singleton births (p < 0.05). The mean score of belief towards breastfeeding was 8.53 (SD = 1.91) and there was no difference between singleton or multiple births.

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Table 2. Bivariate association between singleton/multiple births and Infant feeding and support factors.

https://doi.org/10.1371/journal.pone.0352340.t002

The majority of participants with singleton or multiple births received high social support (76.8%) in Table 2. In terms of postnatal infant feeding support, approximately 50% of participants with singleton or multiple births received postnatal infant feeding support from healthcare professionals, spouses/partners/friends/relatives, or online support group. There was no significant difference in support from health professionals, spouses/partners/friends/relatives between singleton and multiple births, but multiple births were more likely to report receiving support from online support groups during the COVID-19 (p < 0.01). Meanwhile, about 23% reported receiving no support at all for infant feeding during the COVID-19, a higher rate in singleton than in multiple births (p < 0.01).

The most common methods of contacting healthcare professionals for postnatal breastfeeding support were ‘in person (42%)’ followed by ‘by phone (40.8%),’ and ‘video (11.9%)’, but 34.2% said that they never had contacts. Among those who had video contacts for breastfeeding support, 46.1% answered that the supporter could not clearly see the baby latching on, and 43.1% answered that they experienced no difficulties when receiving breastfeeding support video. However, there was no significant difference between singleton and multiple births in terms of (a) method of contacts with a healthcare professional for breastfeeding support and (b) experiencing difficulties when receiving breastfeeding support via video calls.

Multiple logistic regression results on associated factors with multiple births are presented in Table 3. Women with multiple births were significantly associated with their babies fed with infant formula in the last 24 hours (AOR 6.17, 95% CI 2.29–16.57), preterm birth (AOR 5.83, 95% CI 1.99–17.11), and caesarean birth (AOR 2.97, 95% CI 1.27–6.97), and birthweight (AOR 13.16, 95% CI 4.31–40.20 for less than 2.5 kg and AOR 0.11, 95% CI 0.02–0.51 for more than 3.5 kg). Other factors, such as NICU admission, postnatal depression, breastfeeding at breast or expressing breast milk to the baby, the impact of COVID-19 on expressed breast milk, not receiving support for infant feeding, and receiving postnatal infant feeding support from online support groups (e.g., Facebook) were not significantly associated.

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Table 3. Multiple logistic regression analysis of associations between selected factors and multiple births.

https://doi.org/10.1371/journal.pone.0352340.t003

Discussion

Of the 858 eligible participants, 53 (6.2%) experienced multiple births. Out of 640,209 registered births in England and Wales in 2020, 9,656 (1.5%) were multiple births [2]. This demonstrated our sampling size was substantially larger than the population, and that may be because recruitment of participates included via groups which supported families with multiple births. It is important to note that this study cannot attribute differences between multiple and singleton births solely to the COVID-19 pandemic, as no pre-pandemic comparator group was available. Our findings therefore provide cross-sectional associations observed during the pandemic rather than causal inference due to COVID-19 pandemic.

As with the UK national infant feed survey finding [22], our result showed that participants with multiple births were more likely to use infant formula than those with singleton births The physical and emotional challenges of breastfeeding more than one baby, as well as pressure for formula feed from hospital staff [23] might contribute to this finding. Moreover, whilst it was not clear whether those who answered ‘yes’ to this question had been using infant formula exclusively, or as a supplement to breastmilk, it might suggest that they felt it was not possible to sustain their babies’ nutritional needs on breastmilk alone [12]. However breastmilk lactated for multiple births has been shown to be higher in proteins and lower in lactose, when compared to samples taken from women with singleton births [24]. Additionally, when compared to samples collected from parents of multiple births with higher gestational age, breastmilk produced for extremely preterm babies from multiple births contained a significantly higher protein concentration. It was established this could maintain growth and organ development for children with low birthweight [24]. These findings may inform future policy and clinical guidelines, particularly in preparing tailored support for families with multiple births.

Further investigation is required as to whether those who intended to breastfeed wished to do this without using supplementary infant formula and what was needed to achieve this. A Cochrane review [25] found neither evidence from randomised controlled trials on the effectiveness of breastfeeding education and support for women with twins or higher order multiple births, nor the most successful way to provide support. It was not established what would be the best way to deliver the intervention or the timing of care. Current NICE guidelines address the challenges faced by those experiencing multiple pregnancies and differentiate their advice from singleton pregnancies [4]. However, this only pertains to antenatal care and there is a lack of recommendations specifically for postnatal care of those with multiple births. NICE [4] recommends referral to an enhanced team which includes an infant feeding specialist, not as a matter of routine but based on perceived need. However, it also recognized the need for research to be conducted specifically into breastfeeding support for families with multiple births [13]. Considering the obstetric factors associated with multiple births, lactation specialists should be included as members of the multidisciplinary team for all those with multiple births as routine care and not simply when needed. Moreover, future research could take a co-design approach to develop the intervention to support families with multiple births to breastfeed, followed by a robust randomised controlled trial to investigate the effectiveness of the intervention.

Timing of our data collection (July -November 2021) could be a reason that there were no statistically significant results in COVID-19 related factors from our multiple logistic regression analysis as participants were more adjusted to living with COVID-19, reducing the effects of COVID-19 related factors. On the other hand, the positive and negative impact of COVID-19 on breastfeeding, which has been found in other studies [17] has been demonstrated in our participants with multiple births feeding their baby with expressed milk shorter than intended, while also longer than they intended. Having more time at home during COVID-19 [17] might have encouraged feeding directly from the breast and/or expressing breast milk. However, lack of support, including how to express milk, might have turned some women to formula feeding [17]. It has also been found that online group support (e.g., Facebook) is valuable to people multiple births [23]. Virtual breastfeeding support is useful in its convenience and helps breastfeeding practices [26], but its effectiveness when compared to face-to-face consultation is unclear. Future investigation into this technology as a way to provide breastfeeding support could help inform guidance on utilising media and digital technology for future pandemics.

Mahajan et al. [27] found women with multiple births infected with COVID-19 in India had 8 times higher chance of preterm birth when compared to singleton births. This highlighted the high likelihood of those with multiple births having preterm birth [6] as also shown in our finding. This could be due to the presence of more than one foetus in the uterus that puts more physical and physiological stress on the pregnant woman’s body, increasing the possibility of complications leading to premature birth, which is a leading cause of infant morbidity and mortality in the UK [28]. Interventions to reduce the adverse outcomes of preterm birth such as feeding difficulties and maternal problems including anxiety, fatigue and flashbacks [29] should be considered for inclusion in routine maternal support for those with multiple births.

Our result showing caesarean birth was significantly more common in multiple births is consistent with a previous study during COVID-19 in Germany [30]. Due to various complications including high risks of preterm birth, excessive weight gain, placental abruption [31], multiple pregnancies were more likely to result in caesarean birth [5]. Although caesarean birth can be lifesaving, it presents long-term health consequences for women and babies. For example, there were increased risks of miscarriage, still birth, placenta previa, and placental abruption with pregnancies following caesarean birth [32]. Children born by caesarean birth had higher risks of asthma up to age 12 and obesity up to age 5 [32].

While our study did not investigate correlation between the participants who had caesarean birth and those who reported using infant formula, previous research has suggested that the planned mode of birth in multiple births (vaginal vs caesarean birth) did not affect the initiation or continuation of breastfeeding [33]. However, a literature review [34] reported that when compared with vaginal birth, caesarean birth can result in delayed breastfeeding and earlier cessation of exclusive breastfeeding citing physical limitations after surgery, wound pain, anxiety, and breastfeeding inability as predominant barriers. Alongside the higher likelihood of preterm birth and caesarean birth, those with multiple births had higher odds of babies born with birthweight less than 2.5 kg (low birthweight) also concurred with previous research [7,8]. Having babies born with low birthweight was found to increase the women’s risk of having later Type 2 diabetes and cardiovascular disease later in life [35]. Babies born with low birthweight had higher risks of long-term neurologic disability, impaired academic and language development, and cardiovascular disease and diabetes [36]. Babies who fall into this weight category have higher nutritional requirements to ensure they reach the same growth milestones as babies born in higher weight categories and lower their risk of adverse health outcomes [37], and therefore effective feeding support is essential. These results suggested a need for additional support regarding infant nutrition for multiple births.

Conclusions

The study’s findings highlighted that formula feeding, preterm birth, caesarian birth, and birthweight were associated with multiple births during COVID-19 in the UK. This suggests that those with multiple births require tailored breastfeeding support which integrates lactation specialists into their care. Leveraging the use of technology in remote breastfeeding support for those with multiple births is recommended. Further research into effective interventions is needed to improve exclusive breastfeeding rates amongst those with multiple births. Future research should be conducted to investigate how technology can be improved for remote breastfeeding support during and beyond a pandemic.

Acknowledgments

We would like to thank all the participants who completed the survey, and the individuals and organisations who disseminated our survey information.