After 10 months of taking Mounjaro, I’d lost 7st. I thought my nausea and missed periods were just common side-effects of the weight-loss jabs. Then my GP told me what was really going on

When Annabel Dewing’s GP told her she was eight months pregnant, to say she was shocked would be an understatement.

Yes, she’d had sex eight months before – the only time she’d done so that year – but she’d taken the morning-after pill. And her stomach hadn’t shown any of the signs of a growing pregnancy. It was actually smaller than it had been in years.

In fact, her entire body had shrunk dramatically. With the help of Mounjaro, Annabel, 36, had lost an astonishing 7st over the previous ten months. Friends and family had repeatedly told her she’d never looked slimmer. 

Other than missed periods, which she knew could be a side-effect of GLP-1 jabs, Annabel had been aware of no pregnancy symptoms. She’d also put her occasional bouts of nausea – common amongst Mounjaro users – down to the drugs.

What she didn’t realise was that weight-loss jabs can interfere with the effectiveness of contraceptives.

Because GLP-1s slow down the emptying of the stomach, they can also delay the absorption of oral medication. While the Mounjaro patient information leaflet includes a warning about this, Annabel didn’t recall this detail when she took the morning-after pill.

Little wonder, then, that she ‘simply could not compute’ it when she found herself undergoing an emergency ultrasound on February 12 this year and being told she was less than three weeks away from giving birth to her first child.

Her son Alfred arrived, weighing a healthy 6lb 6oz, on March 4. Despite weight-loss medication not being intended for use during pregnancy, he is, so far at least, meeting all his milestones – for which Annabel is ‘unbelievably relieved’.

‘The whole experience has been utterly surreal,’ she tells me. ‘Even after almost three months of night feeds and nappy changes, I’m still struggling to get my head around the fact that I’m a mother. I mean, who gets slimmer and slimmer during pregnancy and has no idea they have a baby growing inside them?’

Until Alfred’s birth, Annabel, who is single, had no plans to have children, devoting all her energies to her career as an estate agent. In April last year, weighing 20st – with a body mass index of 45, making her morbidly obese – she had started Mounjaro, using the jabs for ten months until she reached 13st in January.

Alfred, she now knows, was conceived during a brief relationship in June with a man with whom she had sex just once. As they hadn’t used contraception, and Annabel had no desire to have a baby, she took the morning-after pill. Assuming that had put paid to any chance of a pregnancy, Annabel – who owns a tiny two-bedroom cottage in Dorset – thought nothing more of it.

She had struggled with her weight since her teenage years and by her late 20s weighed around 17st.

Time spent eating and drinking more at home during the pandemic led to her gaining an additional 3st, taking her up to 20st and a size 22.

She struggled to lose weight via a combination of conventional diets, including Slimming World, and exercise. So, in 2024, she tried Ozempic, but quickly gave it up after the drug made her feel unwell. However, a year later Annabel’s sister suggested she give Mounjaro a go, after hearing of people who had struggled with side-effects on Ozempic but were tolerating Mounjaro well.

‘When you get as big as I did, knowing all the health implications and always dressing to hide your body, you’ll try anything,’ says Annabel.

She bought it privately, at £140 for a month’s supply, and started out on the lowest 2.5mg dose.

The results were instant. Annabel was delighted to lose a stone within a month, followed by another stone the next month after moving onto a 5mg dose. She experienced some nausea from the drug but found it tolerable compared with what she’d experienced on Ozempic.

In May 2025 – a month after starting Mounjaro and a month before Alfred’s conception – Annabel’s periods stopped. However, a Google search suggested this was likely due to her rapid weight loss, which can disrupt the hormone signals that control ovulation.

In June 2025, the point she unknowingly conceived, Annabel weighed around 18st. As the months went on, the weight continued to drop off, her stomach ever smaller.

However, with the benefit of hindsight, Annabel recognises there were some other indicators of the little life growing inside her.

She suffered bouts of sciatica, a common pregnancy complaint – though one that can, of course, strike at other times. And a few weeks before that emergency scan in February she had felt, she now realises, the baby kicking. However, as she had stopped her Mounjaro injections two weeks before, she had assumed it was just her stomach rumbling heavily as her body adapted to life without the drug again.

In the end, it was a total stranger who first realised that Annabel – then 13st and a size 14 – was secretly pregnant. She had been showing a client around a house she was selling when the woman asked her: ‘When are you due?’

‘I was taken aback but said: “Oh, I’m not pregnant, I’m just fat,” ’ says Annabel, laughing at the memory.

‘I don’t know who was more embarrassed, her or me. I thought I must already be gaining weight, presuming it was because the effect of the medication had worn off, and vowed to cut back on pizza and pasta.’

However, this off-the-cuff question saw Annabel studying her tummy in the mirror that evening – where she noticed it looked distended and felt hard. Even then, she didn’t suspect she was pregnant; after Googling possible causes of swollen bellies, Annabel feared she might have a tumour, so called her GP.

‘I was pretty terrified and relieved to get an appointment within a couple of days,’ she says. ‘The first thing the doctor asked during the appointment is whether I could be pregnant. I shook my head and said no, but she said she’d need to do a urine test anyway. It felt like an unnecessary formality but I went along with it, keen to get to the bottom of what was going on.

‘Afterwards, she showed me the test stick, saying: “Look, two lines.”

‘In a blind panic I said: “What does that mean?” Of course, on some level, I knew that meant I was pregnant but I just could not take it in.

‘My head was spinning and words were just coming out of my mouth: “What?” “No,” “How?” “I can’t be.”’

While the GP was sympathetic to Annabel’s situation, when she told her the last time she’d had sex was eight months earlier the doctor was understandably concerned about the lack of ante-natal care – not to mention that she had been using Mounjaro throughout. Annabel was told to go straight to the A&E at Dorchester Hospital for a scan.

‘I walked out of the GP’s surgery in a daze and couldn’t get hold of my mum, who was at work, so I called my friend Ali from the car, sobbing and literally shaking with shock,’ recalls Annabel. ‘I kept saying: “The doctor said I’m pregnant. I can’t be”. I don’t think Ali knew what on earth to say – who would? – but she tried to calm me down.

‘I was 20 when my brother was born and I’ve always loved being with him, so the thought of having a child didn’t scare me. It was the prospect of doing it alone – and the expense of it all – that did.’

With no one available to accompany her, Annabel drove to the hospital alone. There she handed over a letter from her GP and said she’d been told to attend for a scan. ‘The receptionist said, knowingly: “Oh yes, we had a call about this.” Then a nurse took me off to check my blood pressure, height and weight before the scan.

‘The sonographer took all the measurements and said the baby seemed to be growing and asked if I wanted to know the sex, which I did. Given she said that the baby was due in 18 days I felt I needed as much information as possible.

‘It was like being in a dream you wake up from. But this was real.’

On top of the surprise of discovering she was about to become a mum, Annabel was understandably concerned about the impact her Mounjaro usage may have had on her unborn child.

While she maintained a balanced diet throughout – porridge or toast for breakfast, a sandwich or baked potato for lunch, and lasagne and salad or chicken and rice for dinner – her appetite was so reduced she ate much smaller portions. Thankfully, Mounjaro had reduced her appetite for alcohol, too.

‘I just knew it couldn’t have been a good thing for me to have eaten so little and lost so much weight at a time when most women are eating for two and putting on at least a couple of stone,’ she says.

‘I didn’t know what the effect might be – poor growth, developmental or some sort of physical deformity – but I felt sick and could hardly sleep even thinking about it.’

Scarier still, none of the doctors at the hospital were able to give reassurances. They said there were no known cases of mums-to-be using GLP-1s beyond the first couple of months of pregnancy.

Although there is limited data when it comes to humans and pregnancy, animal studies have shown that exposure to tirzepatide (Mounjaro’s generic name) during certain stages of development increases the risk of skeletal and organ malformations, as well as reduced foetal growth.

While the doctors told Annabel they had no immediate concerns based on her scans, they warned that her baby would need to be checked over and monitored once he was born.

Fearing there was a risk her unborn son might not even make it, Annabel told only her immediate family and closest friends about the impending birth.

She didn’t even break the news to the father, who she hadn’t seen since the weekend they had sex and who had known she’d taken the morning-after pill. The relationship had been brief as ‘it wasn’t the right time’ for them.

Annabel’s parents, who are divorced, and two sisters were understandably shocked when they heard the news. ‘My dad said: “What? Surely not!” ’ recalls Annabel. ‘When I told Mum she said: “I only saw you two weeks ago and you didn’t look pregnant at all – how is that possible?” I explained that one of the doctors said he might have been “hiding” under my ribs but he was definitely very much there.

‘They’ve both been so supportive and Mum then quickly went into practical mode, setting up a family WhatsApp group with a list of all the things I’d need.’

Obstetricians and paediatricians were keen to check the baby over as soon as possible, so Annabel was booked in for an induction on her due date of March 2. ‘I was dreading the labour, something I’d never even considered going through until a few weeks earlier,’ Annabel admits. After two days of on-off contractions, made bearable by an epidural, Alfred emerged, screaming, on March 4.

Much to Annabel’s relief, he passed all the immediate physical tests, including heart rate, breathing, muscle tone, reflexes and skin colour. ‘Unplanned and unexpected though Alfred was, I sobbed, feeling this huge rush of love the moment I held him in my arms,’ says Annabel.

‘I had this sense that he’d filled a hole I hadn’t realised was there, like I suddenly had a purpose in life. I knew that I’d do whatever it took to give him a good life.

‘I’m quite traditional and always said I’d only have kids if I met someone I really wanted to settle down with. I’d never have planned to be a single mum because I knew it would be very hard work, but I honestly can’t imagine my life without Alfred now. My sisters and friends keep saying he’s been the making of me and I think they’re right. I had no idea how much I’d love being a mum.’

Annabel sent a text message to Alfred’s father shortly after his arrival to share the news and has since sent him photographs.

‘I realise it’s not the best way to communicate something so significant but I wanted to be able to impart all the information in one go, which would have been difficult in a phone call, and I didn’t want to send a letter,’ she says.

‘I understand it must have come as a huge shock to him, as it did to me. He’s a nice guy, so I’d like him to be involved in Alfred’s life if, and when, he feels ready.’

For now, Annabel is being supported by her parents, stepfather, sister and friends – who all adore Alfred as much as Annabel.

However, niggling worries about whether Mounjaro use throughout most of her pregnancy has in any way adversely affected her now 11-week-old son remain.

‘I imagined the doctors would do lots of tests on him but there’s been nothing beyond what they do with any baby,’ Annabel says. ‘I’ve just been told to keep monitoring him and let them know if I have any concerns. So far I don’t, as he’s breastfeeding and sleeping normally, so there’s no cause for alarm.’

When asked to comment on Annabel’s case, a spokesman for Lilly, which manufactures Mounjaro, said: ‘Patient safety is Lilly’s top priority and we actively engage in monitoring, evaluating and reporting safety information for all our medicines. The Summary of Product Characteristics explains that tirzepatide “has the potential to impact the rate of absorption of concomitantly administered oral medicinal products” and that the impact “is most pronounced at the time of tirzepatide treatment initiation”.

‘The tirzepatide Patient Information Leaflet advises that if you are pregnant, think you may be pregnant or are planning to have a baby, ask your doctor for advice before using this medicine.’

Annabel now weighs 13st, a far cry from her starting weight of 20st. Despite the unexpected turn her life has taken, she has nothing but praise for Mounjaro.

‘I feel it saved my life,’ she says. ‘It’s helped me to become so much fitter and healthier, and I would probably have struggled to become pregnant at the weight I was. I’d never have planned my life this way but I love my son beyond words, and because of him – and my new-found health – I’m much happier than I ever thought possible.’