I think you’re totally missing the point here, they’re not saying that teen mums claim benefits for their entire lives, they’re saying that for the period that they are claiming, everything they need is being funded by benefits, and this adds up to way more than the cost of IVF.
To illustrate, a teen single mother with one child living in a 2 bedroom, council tax band B flat in Preston (housing rates vary by area so just an example to do the calculation) would get a standard universal credit allowance of £338.58 per month, an additional £303.94 per month child element, rent paid up to a cap of £132.33 per week and council tax support of £1498.76 per year (£1998.34 band B charge with 25% single person discount applied).
Over the course of 5 years, this amounts to government support of £80.450.75.
In contrast, a 35 year old woman with no children living in Preston (for consistency as the number of funded IVF cycles also varies by area) would be entitled to a single funded cycle of IVF at a cost to the NHS of around £5000-£6000. Taking the midpoint of that range, the teen mother in the example above received over 14.6 times the value of support than the IVF patient. Or putting it another way, the teen mum receives support equivalent to funding one patient’s lifetime entitlement for funded IVF in just over 4 months.
Im not criticising teen mums or older women who seek IVF treatment on the NHS, I’m just pointing out the maths that demonstrates the vast difference between the cost to the taxpayer of the two.