@Tarne
It must be tortuous to know that excess weight is a proven endocrine/hormone disruptor.
rbej.biomedcentral.com/articles/10.1186/s12958-018-0336-z
basically a toxic cocktail that inhibits or stops fetal growth completely, when you don't have the will power or psychological strength to become slimmer and for a baby to grow healthily.
It's so crucial to fetal health it really is in your future baby's and in your best interest to sort this out BEFORE trying to get pregnant if only to increase your chances of a happy, healthy outcome for you and your baby.
I don't think doctors stress this enough to overweight couples because it's such a sensitive and emotive issue but please op, there really is no getting away from this.
I wish you all the best 
Piss. OFF. Your first paragraph is incredibly patronising. For most, not being able to lose weight isn’t a ‘lack of willpower’ and the fact you’d even think that shows how little understanding you have of the obesity crisis. I bet you’re also a calories in Vs calories out subscriber too... read some Gary Taube ffs
Being overweight isn’t a failing of character or morality, in most cases it’s a failing of our system to provide a nutrient rich diet rather than normalising high carb, low nutrient density food as the norm in the name of cheaper food production. Bodies are built differently and how they interact with high carb diets is one of those many differences. As I said, read some Taube. He summarises the problems with modern western diets and the research theyre based on (Angel Keys’ 7 countries study is the root of our modern diet and is deeply flawed research etc).
Secondly, Overweight and yes, even obese women are perfectly capable of having completely normal and healthy pregnancies. In fact, shockingly, perfectly normal, healthy pregnancies are the norm for overweight women. Yes there’s some increased risks to pregnancies in some cases - but you’re presenting you’re argument as if all overweight women will have complex pregnancies when the opposite is true. Historical high blood pressure, a history of drug use, excessive alcohol consumption, excessive exercise or smoking are all much higher risk factors than obesity. IUGR is also not exclusive to obese women - most cases of IUGR occur in women with healthy or underweight BMI’s.
I speak as a woman who’s only living child was conceived and born after a completely straight forward pregnancy when I weighed 21 stone at 5ft 5. My one experience does not a case study make, but it’s posts like yours which terrified me when I found out I was pregnant and there’s absolutely no need for it. Stop presenting nuanced statistics and risk as absolutes - it’s deeply, deeply wrong.
I ate a low carb, high fat diet to get pregnant (PCOS causes insulin resistance, not the other way around). If you have hormonal disruption like PCOS (which is what you’re talking about there), you know about it. Trust me when I say if this is the OP’s issue, she doesn’t need you to tell her.
It’s worth you noting also that Not every fat woman is insulin resistant and not every woman with insulin resistance will develop PCOS. There’s a much higher link between nutrient poverty and PCOS than weight.
The OP will be acutely aware if she has PCOS or if her weight is a barrier to conception, you don’t need to ‘educate’ her.
You might feel it’s your calling in this world to tell fat women they’re weak willed and murdering their own babies with food, but I speak for all fat women when I say DFOD.