Migraleve yelllow is basically just paracetamol and codeine, so yes, will be fine. Most GPs do not realise there is a significant difference between the pink and yellow tablets I've found...if in doubt, ask a pharmacist and properly quiz them about the properties of each one. For example, Syndol is my drug of choice out of pg mainly because it has the highest dose of codeine and a decent balance of other helpers of all the OTC ones, but GPs often do not know this.
Codeine in itself has not been proven to harm lung development in itself (i.e. it probably won't cause abnormalities in itself) I think it's only near term that codeine is an issue, as it's the action of breathing that's subdued, so prolongued usage in 3rd trimester isn't advised - BUT think of all the Mums out there with SPD and the likes, they're not going to function at all without codeine and on the whole, their babies are 100% normal. I was also on codeine for a spell at 31-34wks and was told if LO made an appearance her breathing would be more sluggish and possibly 'delayed' because of the opoids as her responses would be slower, BUT the main issue then was preamturity and stopping my contractions and lowering our heartrates. It makes baby's nervous system confused and sluggish. Opoid abuse babies often need help with breathing when born etc as their systems are out of kilter. Babies that of Mums that have had opoids durng labour often have lower APGAR scores for example.
You will be told the same thing about pethidine and fentanyl (though this is faster dealt with by the body and given in 'weaker' more targeted doses and not everywhere offers this). These are routinely given to birthing mothers, though each one is often used at different stages...and baby will be monitored if you've been given these to look for fetal distress.
Because there have been no controlled studies done however, caution is advised and if at all possible, don't take codeine. BUT with all things in pregnancy, it's a risk vs benifits thing. The stress and distress and flooding of your 'natural' adrenalines etc of a refractory migraine could do just as much damage to baby or you as taking an opoid...
Imigran (sumatriptan) is a triptain and a totally different drug type, and abortive (in that is should stop the migraine, not just help you through it). Not ideal for babies because it's designed to inhibit the effects of seratonin (one theroy of why migraines happen is a wonky seratonin production system)... which isn't ideal is you don't have a migraine and are trying to grow your brain (like babies do)!
I have plenty of tops for helping ease a migraine (from me and others) if you want me to post them. Some have worked for me, some not, but if you're a regular migraineur then you'll probably know what you can and can't do to feel better.