Alfonso, I have located the following literature for you. I would also suggest finding systematic reviews on the topic. Good Luck with your Masters Thesis. Cheers James.

References:

Sandra L.Hofferth. Risking the Future: Adolescent Sexuality, Pregnancy, and Childbearing, Volume II: Working Papers and Statistical Appendices.

Risking the Future: Adolescent Sexuality, Pregnancy, and Childbearing, Volume II: Working Papers and Statistical Appendices (1987). https://www.nap.edu/login.php?record_id=946&page=https%3A%2F%2Fwww.nap.edu%2Fdownload%2F946

Morinis J, Carson C, Quigley MA. Effect of teenage motherhood on cognitive outcomes in children: a population-based cohort study. .Archives of Disease in Childhood Published Online First: 14 October 2013. doi: 10.1136/archdischild-2012-302525

Schuyler Center for Analysis and Advocacy. (2008). Teenage Births: Outcomes for Young Parents and their Children. http://www.scaany.org/documents/teen_pregnancy_dec08.pdf

Paniagua, M.N. & Walker, I. (2012). The Impact of Teenage Motherhood on the Education and Fertility of their Children: Evidence for Europe. Discussion Paper No. 69895.  http://ftp.iza.org/dp6995.pdf

Gueorguieva et al (2000). Effect of Teenage Pregnancy on Educational Disabilities in Kindergarten. American Journal of Epidemiology. 154(3). pp.212-220. https://oup.silverchair-cdn.com/oup/backfile/Content_public/Journal/aje/154/3/10.1093_aje_154.3.212/1/212.pdf?Expires=1490263318&Signature=UidaUhBAolCGDkLC~mNq6JX4UDQrXfRHQGzDjp-mN4N~j2N9LBgPvq1IHI5wRUjri9S6SYGoojQLPCpjs8PhVzxmB7HyQnrFLOOq9siqjFwsPiqXlEdDZf9h5CTX4Of3C6PWxNnt5k27J6MaEf2v3R7Hqu8OFO6uZUMPJbCrlj~u2ULdt-kpXwIcu3xMnII3pQRcWXxNQQJEWCj1uIOgfD0FYHsIqt9myoKOUiO5yulFyEyi7JY4pXGLhzX~UrxejbdK~qFRPSS-cHLmzAAjuvvrftPYsfx5cywP3oDvUXRmK54KhN06DAqMDbisWb3ZYh0fgGee5ZG2s3cCdzDnvw__&Key-Pair-Id=APKAIUCZBIA4LVPAVW3Q

How Adolescent Parenting Affects Children, Families, and Communities.

http://www.urbanchildinstitute.org/articles/editorials/how-adolescent-parenting-affects-children-families-and-communities

Barmao-Kiptanui et al (2015). International Journal of Educational Administration and Policy Studies Full Length Research Paper. Impact of teenage motherhood on the academic performance in public primary schools in Bungoma County, Kenya Vol. 7(2), pp. 61-71. http://www.academicjournals.org/article/article1427875021_Barmao-Kiptanui%20et%20al.pdf

Arnett, J. J. (2006). Emerging adulthood: Understanding the new way of coming of age. In J. J. Arnett & J. L. Tanner (Eds.), Emerging adults in America: Coming of age in the 21st century. Washington, DC: American Psychological Association.

Bennett, C. M., & Baird, A. A. (2006). Anatomical changes in the emerging adult brain: A voxel-based morphometry study. Human Brain Mapping, 27(9), 766–777.

Duncan, S. (2007). What’s the problem with teenage parents? And what’s the problem with policy? Critical Social Policy, 27(3), 307–334.

Boulden, K. (2003). Step by step, side by side: how to make your school a great choice for pregnant and parenting students. Queensland: Association of Women Educators Inc.

Berlyn, C., Wise, S., & Soriano, G. (2008). Engaging fathers in child and family services. Canberra: Department of Families, Housing, Community Services and Indigenous Affairs.

Fergusson, D. M., & Woodward, L. J. (2000). Teenage pregnancy and female educational underachievement: A prospective study of a New Zealand birth cohort. Journal of Marriage and Family, 62(1), 147–161.

Jaffee, S. R. (2002). Pathways to adversity in young adulthood among early childbearers. Journal of Family Psychology,

16(1), 38–49.

McDermott, E., & Graham, H. (2005). Resilient young mothering: Social inequalities, late modernity and the “problem” of “teenage” motherhood. Journal of Youth Studies, 8(1), 59–79.

Mendes, P. (2009). Improving outcomes for teenage pregnancy and early parenthood for young people in out-of-home care: A review of the literature. Youth

Woodward, L. J., Horwood, L. J., & Fergusson, D. M. (2001). Teenage pregnancy: Cause for concern. New Zealand Medical Journal, 114(1135), 301–303.

Rhein, L. M., Ginsburg, K. R., Schwarz, D. F., Pinto-Martin, J. A., Zhao, H., Morgan, A. P., et al. (1997). Teen father participation in child rearing: Family perspectives. Journal of Adolescent Health, 21(4), 244–252.

Australian Institute of family Studies. (2013). Family factors in early school leaving. https://aifs.gov.au/cfca/publications/family-factors-early-school-leaving/introduction

Khatun M, Al, Mamun A, Scott J, William GM, Clavarino A, Najman JM (2017). Do children born to teenage parents have lower adult intelligence ? A prospective birth cohort study. PloS ONE 12(3): e0167395. doi:10.1371/journal.pone.0167395.

http://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0167395&type=printable

Xie et al (2014). Academic performance, educational aspiration and birth outcomes among adolescent mothers: a national longitudinal study. BMC Pregnancy and Childbirth, 14:(3), 1-11. http://download.springer.com/static/pdf/511/art%253A10.1186%252F1471-2393-14-3.pdf?originUrl=http%3A%2F%2Fbmcpregnancychildbirth.biomedcentral.com%2Farticle%2F10.1186%2F1471-2393-14-3&token2=exp=1489919203~acl=%2Fstatic%2Fpdf%2F511%2Fart%25253A10.1186%25252F1471-2393-14-3.pdf*~hmac=e303eacb761fed7d1a15f05a03b303b310e7ba6dba3e8cee3596eed43f6dfb66

Brown, A. (2008). CHILDREN OF TEENAGE MOTHERS: SCHOOL READINESS OUTCOMES AND PREDICTORS OF SCHOOL SUCCESS. Doctoral Thesis. UNIVERSITY OF NORTH TEXAS. https://digital.library.unt.edu/ark:/67531/metadc9117/m2/1/high_res_d/dissertation.pdf

St. Michael's Hospital. Children born to teen mothers have delayed development, likely due to social factors. https://www.sciencedaily.com/releases/2013/10/131016213050.htm

Morinis, J., Carson, C.M. & Quigley. A. Effect of teenage motherhood on cognitive outcomes in children: a population-based cohort study. Archives of Disease in Childhood, 2013; DOI: 10.1136/archdischild-2012-302525

Dear Alphonso:

You ask the following: How does teenage motherhood affect the cognitive outcomes and academic achievement of teenage mothers' children? Let me say that this is a nice topic for your MA thesis. 

It is often the case that a question can give rise to a short or long answer. As I see it, James provided you with abundant literature related to your question. My answer to your question will be a short answer. Let me begin by saying that in order to be successful, any parenting and, hence, motherhood, should aim at promoting the child's cognitive, moral and aesthetical development. Note that the true, the good, and the beautiful are universal categories, regardless of how they are seen at different places and times. Unfortunately, schools and families often emphasize the cognitive at the cost of the good and the beautiful. For example, it is often said  that schools and families are much more oriented to three " Rs" (reading, writing, and reasoning) than the three "Cs" (care, concern, and connection). It would be nice of you that your thesis also referred, for example, to how teenage motherhood affects the moral and aesthetical outcomes of teenage mothers' children. Of course , this is not mandatory, only a suggestion. By so doing, you would have a Kantian theoretical framework for your dissertation. Note that Kant wrote three Critiques, one dedicated to the true (Critical of Pure Reason); one dedicated to the good (Critical of Practical Reason), and one related to the beautiful (Critique of Judgment). In this vein, we might say that Piaget's oeuvre is devoted to the scientific study of true, that Kohlberg's theory is dedicated to the scientific study of the good. Kant's Critique of Judgment still waits for being seriously addressed in developmental psychology.

Are you acquainted with Diane Baumrind's styles of parenting, be it seen from the father's or mother's perspective? She conceptualized three types of parenting/motherhood/fatherhood. Authoritative, authoritarian, and permissive, Authoritative motherhood is demanding but warm; authoritarian motherhood is demanding but cold; permissive parenting is guided, say, by the slogan "laissez faire, laissez passer, laissez aller (Let's it go)".

There is amassing evidence that shows that an authoritative motherhood or fatherhood has beneficial effects on the child's cognitive, moral, pro-social, emotional, and aesthetical development. This is not the case of either an authoritarian or permissive parenting. In a  permissive parenting, for example, the child is left, say, at complete darkness in terms of any logical rule, or moral norm. Note, however, that a world deprived of any truth would be illogical and aberrant, and deprived of any moral norm or principle would be unjust and immoral.

I also wonder whether you are acquainted with Martin Hoffman’s classical thinking about the discipline strategies that parents, be they mothers or fathers, appeal while dealing with misdeeds of several types committed by their children in their everyday life, namely at home. More precisely, Hoffman [see Hoffman, M. (1970). Moral development. In P. Mussen (Ed.), Carmichael's manual of child psychology (Vol. 2. pp. 261-360). New York: Wiley] studied children’s moral reasoning and development as a function of the type of discipline strategies parents employ while dealing with misbehavior committed by their children in their everyday life. Children’s moral development was seen in Piagetian terms [see Piaget, J. (1932). The moral development of the child)].As you certainly know,Piaget distinguished moral heteronomy, a morality oriented to the idea of fear, obedience and unilateral respect, from moral autonomy, a more advanced form of morality, a morality guided by the idea of equality, cooperation, and bilateral respect.

Hoffman conceptualized three types of such discipline strategies: Power assertion, withdrawal of love and inductive or explanatory practices. There is power assertion when parents “… try to control the child’s behavior by appealing to their physical power or their control of certain resources…” such as toys, fruit-gums, and the like (Hoffman, 1970, p. 285). (e.g., “if you do that, to lie, for instance, you won’t have toys anymore”. Withdrawal of love is a kind of blackmail in that parents try to control the child’s behavior by threatening him/her with unpleasant psychological consequences, such as, “if you do that -- to hit your sister, for example -- mom does not like you anymore”. Thus, in the withdrawal of love strategy “… parents give a direct, albeit not physical, expression of their disapproval of the child’s transgressions.” (p. 285). Contrary to what happens with power assertion and withdrawal of love, when inductive or explanatory practices are used, parents try to get the child’s adherence by explaining to him/her the negative effects of his/her misdeeds on others (e.g.,” if you hit your sister she will be hurt”).

Among other things, Hoffman found that such discipline strategies or practices were related to different levels of children’s moral development. For example, he found (see p.292) that the frequent use of power assertion on the part of the mother was consistently associated with a low level of children’s moral development, such as is the case of moral heteronomy. In contradistinction, inductive practices were positively associated with the child’s moral autonomy. In a nutshell, discipline strategies a la Hoffman are a good predictor of children’s moral development. As there is mounting evidence that shows that one’s cognitive and social development are a necessary, albeit not sufficient, condition of one’s moral development, Hoffman’s parenting  strategies are also, to an extent, a predictor of children’s cognitive and social development. .     

As far as I know there is no standardized tool to assess both Baumrin's styles of parenting and Hoffman’s discipline strategies. This means that if you want to appeal to such strategies as predictors of developmental outcomes you have to conduct a semi-structured. This is not bad, I think. Actually, psychologists often make use, for example, of standardized like-Likert scales. By so doing, they believe and get the impression – I would say the illusion -- that they are really measuring a certain psychological construct, such cognitive, moral, social, emotional, or aesthetical development. This is one of the reasons why I think that in psychology we should say to evaluate or assess, not to measure. Suffice it to say that, for example, in a Likert-scale the same score (40, for instance) can be obtained or achieved by answering differently to the several items of the scale at hand. The belief mentioned above is greatly responsible for what the Neo-Popperian Paul Meehl once called “the slow progress of soft psychology “[See Meehl, P. (1978) Theoretical risks and tabular asterisks: Sir Karl, Sir Ronald, and the slow progress of softy psychology. Journal of Consulting and Clinical Psychology, 46, 806-834].

 Note also, that Piaget’s monumental theory of cognitive development never appealed to generally and theoretically ungrounded standardized scales or (mental) tests but rather to theoretically grounded interviews and developmental tasks. To see the difference between mental tests and developmental tasks a la Piaget, note that the former are referred to a quantitative norm, and the latter to a qualitative criterion. In other words, Piaget’s idea was to assess the type of one’s intelligence (i.e., to know better) than the quantity of one’s intelligence (i.e., to know more of the same).

I hope that I have got your points and that this helps.   

Best regards.